11th Commerce Maths 1 Chapter 4 Miscellaneous Exercise 4 Answers Maharashtra Board

Sequences and Series Class 11 Commerce Maths 1 Chapter 4 Miscellaneous Exercise 4 Answers Maharashtra Board

Balbharati Maharashtra State Board 11th Commerce Maths Solution Book Pdf Chapter 4 Sequences and Series Miscellaneous Exercise 4 Questions and Answers.

Std 11 Maths 1 Miscellaneous Exercise 4 Solutions Commerce Maths

Question 1.
In a G.P., the fourth term is 48 and the eighth term is 768. Find the tenth term.
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 4 Sequences and Series Miscellaneous Exercise 4 Q1

Question 2.
For a G.P. a = \(\frac{4}{3}\) and t7 = \(\frac{243}{1024}\), find the value of r.
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 4 Sequences and Series Miscellaneous Exercise 4 Q2

Maharashtra Board 11th Commerce Maths Solutions Chapter 4 Sequences and Series Miscellaneous Exercise 4

Question 3.
For a sequence, if tn = \(\frac{5^{n-2}}{7^{n-3}}\), verify whether the sequence is a G.P. If it is a G.P., find its first term and the common ratio.
Solution:
The sequence (tn) is a G.P., if \(\frac{5^{n-2}}{7^{n-3}}\) = constant, for all n ∈ N.
Maharashtra Board 11th Commerce Maths Solutions Chapter 4 Sequences and Series Miscellaneous Exercise 4 Q3
∴ the sequence is a G.P. with common ratio = \(\frac{5}{7}\)
∴ first term = t1 = \(\frac{5^{1-2}}{7^{1-3}}=\frac{5^{-1}}{7^{-2}}=\frac{7^{2}}{5}=\frac{49}{5}\)

Question 4.
Find three numbers in G.P., such that their sum is 35 and their product is 1000.
Solution:
Let the three numbers in G.P. be \(\frac{a}{r}\), a, ar.
According to the first condition,
Maharashtra Board 11th Commerce Maths Solutions Chapter 4 Sequences and Series Miscellaneous Exercise 4 Q4
Maharashtra Board 11th Commerce Maths Solutions Chapter 4 Sequences and Series Miscellaneous Exercise 4 Q4.1
∴ the three numbers in G.P. are 20, 10, 5 or 5, 10, 20.

Question 5.
Find 4 numbers in G. P. such that the sum of the middle 2 numbers is \(\frac{10}{3}\) and their product is 1.
Solution:
Let the four numbers in G.P. be \(\frac{a}{r^{3}}, \frac{a}{r}, a r, a r^{3}\).
According to the second condition,
\(\frac{\mathrm{a}}{\mathrm{r}^{3}}\left(\frac{\mathrm{a}}{\mathrm{r}}\right)(\mathrm{ar})\left(\mathrm{ar}^{3}\right)=1\)
∴ a4 = 1
∴ a = 1
According to the first condition,
Maharashtra Board 11th Commerce Maths Solutions Chapter 4 Sequences and Series Miscellaneous Exercise 4 Q5

Maharashtra Board 11th Commerce Maths Solutions Chapter 4 Sequences and Series Miscellaneous Exercise 4

Question 6.
Find five numbers in G.P. such that their product is 243 and the sum of the second and fourth numbers is 10.
Solution:
Let the five numbers in G.P. be
\(\frac{a}{r^{2}}, \frac{a}{r}, a, a r, a r^{2}\)
According to the first condition,
Maharashtra Board 11th Commerce Maths Solutions Chapter 4 Sequences and Series Miscellaneous Exercise 4 Q6
Maharashtra Board 11th Commerce Maths Solutions Chapter 4 Sequences and Series Miscellaneous Exercise 4 Q6.1

Question 7.
For a sequence, Sn = 4(7n – 1), verify whether the sequence is a G.P.
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 4 Sequences and Series Miscellaneous Exercise 4 Q7

Question 8.
Find 2 + 22 + 222 + 2222 + …… upto n terms.
Solution:
Sn = 2 + 22 + 222 +….. upto n terms
= 2(1 + 11 + 111 +…… upto n terms)
= \(\frac{2}{9}\) (9 + 99 + 999 + … upto n terms)
= \(\frac{2}{9}\) [(10 – 1) + (100 – 1) + (1000 – 1) +…… upto n terms]
= \(\frac{2}{9}\) [(10 + 100 + 1000 + … upto n terms) – (1 + 1 + 1 + ….. n times)]
Since, 10, 100, 1000, …… n terms are in G.P.
with a = 10, r = \(\frac{100}{10}\) = 10
Maharashtra Board 11th Commerce Maths Solutions Chapter 4 Sequences and Series Miscellaneous Exercise 4 Q8

Question 9.
Find the nth term of the sequence 0.6, 0.66, 0.666, 0.6666,…..
Solution:
0.6, 0.66, 0.666, 0.6666, ……
∴ t1 = 0.6
t2 = 0.66 = 0.6 + 0.06
t3 = 0.666 = 0.6 + 0.06 + 0.006
Hence, in general
tn = 0.6 + 0.06 + 0.006 + …… upto n terms.
The terms are in G.P.with
a = 0.6, r = \(\frac{0.06}{0.6}\) = 0.1
∴ tn = the sum of first n terms of the G.P.
Maharashtra Board 11th Commerce Maths Solutions Chapter 4 Sequences and Series Miscellaneous Exercise 4 Q9

Maharashtra Board 11th Commerce Maths Solutions Chapter 4 Sequences and Series Miscellaneous Exercise 4

Question 10.
Find \(\sum_{r=1}^{n}\left(5 r^{2}+4 r-3\right)\).
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 4 Sequences and Series Miscellaneous Exercise 4 Q10

Question 11.
Find \(\sum_{\mathbf{r}=1}^{\mathbf{n}} \mathbf{r}(\mathbf{r}-\mathbf{3})(\mathbf{r}-\mathbf{2})\).
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 4 Sequences and Series Miscellaneous Exercise 4 Q11
Maharashtra Board 11th Commerce Maths Solutions Chapter 4 Sequences and Series Miscellaneous Exercise 4 Q11.1

Question 12.
Find \(\sum_{r=1}^{n} \frac{1^{2}+2^{2}+3^{2}+\ldots+r^{2}}{2 r+1}\)
Solution:
We know that,
Maharashtra Board 11th Commerce Maths Solutions Chapter 4 Sequences and Series Miscellaneous Exercise 4 Q12

Question 13.
Find \(\sum_{r=1}^{n} \frac{1^{3}+2^{3}+3^{3}+\ldots+r^{3}}{(r+1)^{2}}\)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 4 Sequences and Series Miscellaneous Exercise 4 Q13
Maharashtra Board 11th Commerce Maths Solutions Chapter 4 Sequences and Series Miscellaneous Exercise 4 Q13.1

Question 14.
Find 2 × 6 + 4 × 9 + 6 × 12 + …… upto n terms.
Solution:
2, 4, 6, … are in A.P.
∴ rth term = 2 + (r – 1)2 = 2r
6, 9, 12, … are in A.P.
∴ rth term = 6 + (r – 1) (3) = (3r + 3)
∴ 2 × 6 + 4 × 9 + 6 × 12 +…… upto n terms
Maharashtra Board 11th Commerce Maths Solutions Chapter 4 Sequences and Series Miscellaneous Exercise 4 Q14
= n(n + 1) (2n + 1 + 3)
= 2n(n + 1)(n + 2)

Maharashtra Board 11th Commerce Maths Solutions Chapter 4 Sequences and Series Miscellaneous Exercise 4

Question 15.
Find 122 + 132 + 142 + 152 + …… + 202.
Solution:
122 + 132 + 142 + 152 + …… + 202
= (12 + 22 + 32 + 42 + ……. + 202) – (12 + 22 + 32 + 42 + …… + 112)
Maharashtra Board 11th Commerce Maths Solutions Chapter 4 Sequences and Series Miscellaneous Exercise 4 Q15
= 2870 – 506
= 2364

Question 16.
Find (502 – 492) + (482 – 472) + (462 – 452) + …… + (22 – 12).
Solution:
(502 – 492) + (482 – 472) + (462 – 452) + …… + (22 – 12)
= (502 + 482 + 462 + …… + 22) – (492 + 472 + 452 + …… + 12)
= \(\sum_{r=1}^{25}(2 r)^{2}-\sum_{r=1}^{25}(2 r-1)^{2}\)
Maharashtra Board 11th Commerce Maths Solutions Chapter 4 Sequences and Series Miscellaneous Exercise 4 Q16
= 1300 – 25
= 1275

Question 17.
In a G.P., if t2 = 7, t4 = 1575, find r.
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 4 Sequences and Series Miscellaneous Exercise 4 Q17

Question 18.
Find k so that k – 1, k, k + 2 are consecutive terms of a G.P.
Solution:
Since k – 1, k, k + 2 are consecutive terms of a G.P.
∴ \(\frac{k}{k-1}=\frac{k+2}{k}\)
∴ k2 = k2 + k – 2
∴ k – 2 = 0
∴ k = 2

Maharashtra Board 11th Commerce Maths Solutions Chapter 4 Sequences and Series Miscellaneous Exercise 4

Question 19.
If pth, qth and rth terms of a G.P. are x, y, z respectively, find the value of \(x^{q-r} \cdot y^{r-p} \cdot z^{p-q}\).
Solution:
Let a be the first term and R be the common ratio of the G.P.
∴ tn = \(\text { a. } R^{n-1}\)
∴ x = \(\text { a. } R^{p-1}\), y = \(\text { a. } R^{q-1}\), z = \(\text { a. } R^{r-1}\)
Maharashtra Board 11th Commerce Maths Solutions Chapter 4 Sequences and Series Miscellaneous Exercise 4 Q19

11th Commerce Maths Digest Pdf

11th Commerce Maths 1 Chapter 3 Exercise 3.1 Answers Maharashtra Board

Complex Numbers Class 11 Commerce Maths 1 Chapter 3 Exercise 3.1 Answers Maharashtra Board

Balbharati Maharashtra State Board 11th Commerce Maths Solution Book Pdf Chapter 3 Complex Numbers Ex 3.1 Questions and Answers.

Std 11 Maths 1 Exercise 3.1 Solutions Commerce Maths

Question 1.
Write the conjugates of the following complex numbers:
(i) 3 + i
(ii) 3 – i
(iii) -√5 – √7i
(iv) -√-5
(v) 5i
(vi) √5 – i
(vii) √2 + √3i
Solution:
(i) Conjugate of (3 + i) is (3 – i)
(ii) Conjugate of (3 – i) is (3 + i)
(iii) Conjugate of (-√5 – √7i) is (-√5 + √7i)
(iv) -√-5 = -√5 × √-1 = -√5i
Conjugate of -√-5 is √5i
(v) Conjugate of 5i is -5i
(vi) Conjugate of √5 – i is √5 + i
(vii) Conjugate of √2 + √3i is √2 – √3i

Maharashtra Board 11th Commerce Maths Solutions Chapter 3 Complex Numbers Ex 3.1

Question 2.
Express the following in the form of a + ib, a, b ∈ R, i = √-1. State the values of a and b:
(i) (1 + 2i)(-2 + i)
(ii) \(\frac{\mathrm{i}(4+3 \mathrm{i})}{(1-\mathrm{i})}\)
(iii) \(\frac{(2+i)}{(3-i)(1+2 i)}\)
(iv) \(\frac{3+2 i}{2-5 i}+\frac{3-2 i}{2+5 i}\)
(v) \(\frac{2+\sqrt{-3}}{4+\sqrt{-3}}\)
(vi) (2 + 3i)(2 – 3i)
(vii) \(\frac{4 i^{8}-3 i^{9}+3}{3 i^{11}-4 i^{10}-2}\)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 3 Complex Numbers Ex 3.1 Q2
Maharashtra Board 11th Commerce Maths Solutions Chapter 3 Complex Numbers Ex 3.1 Q2.1
Maharashtra Board 11th Commerce Maths Solutions Chapter 3 Complex Numbers Ex 3.1 Q2.2
Maharashtra Board 11th Commerce Maths Solutions Chapter 3 Complex Numbers Ex 3.1 Q2.3
Maharashtra Board 11th Commerce Maths Solutions Chapter 3 Complex Numbers Ex 3.1 Q2.4
Maharashtra Board 11th Commerce Maths Solutions Chapter 3 Complex Numbers Ex 3.1 Q2.5

Question 3.
Show that (-1 + √3i)3 is a real number.
Solution:
(-1 + √3i)3
= (-1)3 + 3(-1)2 (√3i) + 3(-1)(√3i)2 +(√3i)3 [∵ (a + b)3 = a3 + 3a2b + 3ab2 + b3]
= -1 + 3√3i – 3(3i2) + 3√3 i3
= -1 + 3√3i – 3(-3) – 3√3i [∵ i2 = -1, i3 = -1]
= -1 + 9
= 8, which is a real number.

Question 4.
Evaluate the following:
(i) i35
(ii) i888
(iii) i93
(iv) i116
(v) i403
(vi) \(\frac{1}{i^{58}}\)
(vii) i30 + i40 + i50 + i60
Solution:
We know that, i2 = -1, i3 = -i, i4 = 1
(i) i35 = (i4)8 (i2) i = (1)8 (-1) i = -i
(ii) i888 = (i4)222 = (1)222 = 1
(iii) i93 = (i4)23 . i = (1)23 . i = i
(iv) i116 = (i4)29 = (1)29 = 1
(v) i403 = (i4)100 (i2) i = (1)100 (-1) i = -i
(vi) \(\frac{1}{i^{88}}=\frac{1}{\left(i^{4}\right)^{14} \cdot i^{2}}=\frac{1}{(1)^{14}(-1)}=-1\)
(vii) i30 + i40 + i50 + i60
= (i4)7 i2 + (i4)10 + (i4)12 i2 + (i4)15
= (1)7 (-1) + (1)10 + (1)12 (-1) + (1)15
= -1 + 1 – 1 + 1
= 0

Maharashtra Board 11th Commerce Maths Solutions Chapter 3 Complex Numbers Ex 3.1

Question 5.
Show that 1 + i10 + i20 + i30 is a real number.
Solution:
1 + i10 + i20 + i30
= 1 + (i4)2 . i2 + (i4)5 + (i4)7 . i2
= 1 + (1)2 (-1) + (1)5 + (1)7 (-1) [∵ i4 = 1, i2 = -1]
= 1 – 1 + 1 – 1
= 0, which is a real number.

Question 6.
Find the value of
(i) i49 + i68 + i89 + i110
(ii) i + i2 + i3 + i4
Solution:
(i) i49 + i68 + i89 + i110
= (i4)12 . i + (i4)17 + (i4)22 . i + (i4)27 . i2
= (1)12 . i + (1)17 + (1)22 . i + (1)27(-1) ……[∵ i4 = 1, i2 = -1]
= i + 1 + i – 1
= 2i

(ii) i + i2 + i3 + i4
= i + i2 + i2 . i + i4
= i – 1 – i + 1 [∵ i2 = -1, i4 = 1]
= 0

Question 7.
Find the value of 1 + i2 + i4 + i6 + i8 + …… + i20.
Solution:
1 + i2 + i4 + i6 + i8 + ….. + i20
= 1 + (i2 + i4) + (i6 + i8) + (i10 + i12) + (i14 + i16) + (i18 + i20)
= 1 + [i2 + (i2)2] + [(i2)3 + (i2)4] + [(i2)5 + (i2)6] + [(i2)7 + (i2)8] + [(i2)9 + (i2)10]
= 1 + [-1 + (- 1)2] + [(-1)3 + (-1)4] + [(-1)5 + (-1)6] + [(-1)7 + (-1)8] + [(-1)9 + (-1)10] [∵ i2 = -1]
= 1 + (-1 + 1) + (-1 + 1) + (-1 + 1) + (-1 + 1) + (-1 + 1)
= 1 + 0 + 0 + 0 + 0 + 0
= 1

Question 8.
Find the values of x and y which satisfy the following equations (x, y ∈ R):
(i) (x + 2y) + (2x – 3y)i + 4i = 5
(ii) \(\frac{x+1}{1+\mathrm{i}}+\frac{y-1}{1-\mathrm{i}}=\mathrm{i}\)
Solution:
(i) (x + 2y) + (2x – 3y)i + 4i = 5
∴ (x + 2y) + (2x – 3y)i = 5 – 4i
Equating real and imaginary parts, we get
x + 2y = 5 ……..(i)
and 2x – 3y = -4 ………(ii)
Equation (i) × 2 – equation (ii) gives
7y = 14
∴ y = 2
Putting y- 2 in (i), we get
x + 2(2) = 5
∴ x + 4 = 5
∴ x = 1
∴ x = 1 and y = 2
Check:
If x = 1 and y = 2 satisfy the given condition, then our answer is correct.
L.H.S. = (x + 2y) + (2x – 3y)i + 4i
= (1 + 4) + (2 – 6)i + 4i
= 5 – 4i + 4i
= 5
= R.H.S.
Thus, our answer is correct.

(ii) \(\frac{x+1}{1+\mathrm{i}}+\frac{y-1}{1-\mathrm{i}}=\mathrm{i}\)
Maharashtra Board 11th Commerce Maths Solutions Chapter 3 Complex Numbers Ex 3.1 Q8
(x + y) + (y – x – 2)i = 2i
(x + y) + (y – x – 2)i = 0 + 2i
Equating real and imaginary parts, we get
x + y = 0 and y – x – 2 = 2
∴ x + y = 0 ……(i)
and -x + y = 4 ……..(ii)
Adding (i) and (ii), we get
2y = 4
∴ y = 2
Putting y = 2 in (i), we get
x + 2 = 0
∴ x = -2
∴ x = -2 and y = 2

Maharashtra Board 11th Commerce Maths Solutions Chapter 3 Complex Numbers Ex 3.1

Question 9.
Find the value of:
(i) x3 – x2 + x + 46, if x = 2 + 3i
(ii) 2x3 – 11x2 + 44x + 27, if x = \(\frac{25}{3-4 i}\)
Solution:
(i) x = 2 + 3i
∴ x – 2 = 3i
∴ (x – 2)2 = 9i2
∴ x2 – 4x + 4 = 9(-1) …..[∵ i2 = -1]
∴ x2 – 4x + 13 = 0 ……(i)
Maharashtra Board 11th Commerce Maths Solutions Chapter 3 Complex Numbers Ex 3.1 Q9
∴ x3 – x2 + x + 46 = (x2 – 4x + 13)(x + 3) + 7
= 0(x + 3) + 7 ……[From (i)]
= 7

(ii) x = \(\frac{25}{3-4 i}\)
Maharashtra Board 11th Commerce Maths Solutions Chapter 3 Complex Numbers Ex 3.1 Q9.1
∴ x = 3 + 4i
∴ x – 3 = 4i
∴ (x – 3)2 = 16i2
∴ x2 – 6x + 9 = 16(-1) …….[∵ i2 = -1]
∴ x2 – 6x + 25 = 0 …….(i)
Maharashtra Board 11th Commerce Maths Solutions Chapter 3 Complex Numbers Ex 3.1 Q9.2
∴ 2x3 – 11x2 + 44x + 27
= (x2 – 6x + 25) (2x + 1) + 2
= 0 . (2x + 1) + 2 ……[From (i)]
= 0 + 2
= 2

11th Commerce Maths Digest Pdf 

11th Commerce Maths 1 Chapter 7 Miscellaneous Exercise 7 Answers Maharashtra Board

Limits Class 11 Commerce Maths 1 Chapter 7 Miscellaneous Exercise 7 Answers Maharashtra Board

Balbharati Maharashtra State Board 11th Commerce Maths Solution Book Pdf Chapter 7 Limits Miscellaneous Exercise 7 Questions and Answers.

Std 11 Maths 1 Miscellaneous Exercise 7 Solutions Commerce Maths

I.

Question 1.
If \(\lim _{x \rightarrow 2} \frac{x^{n}-2^{n}}{x-2}=80\) then find the value of n.
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Miscellaneous Exercise 7 I Q1

II. Evaluate the following Limits:

Question 1.
\(\lim _{x \rightarrow a} \frac{(x+2)^{\frac{5}{3}}-(a+2)^{\frac{5}{3}}}{x-a}\)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Miscellaneous Exercise 7 II Q1

Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Miscellaneous Exercise 7

Question 2.
\(\lim _{x \rightarrow 0} \frac{(1+x)^{n}-1}{x}\)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Miscellaneous Exercise 7 II Q2
Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Miscellaneous Exercise 7 II Q2.1

Question 3.
\(\lim _{x \rightarrow 2}\left[\frac{(x-2)}{2 x^{2}-7 x+6}\right]\)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Miscellaneous Exercise 7 II Q3

Question 4.
\(\lim _{x \rightarrow 1}\left[\frac{x^{3}-1}{x^{2}+5 x-6}\right]\)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Miscellaneous Exercise 7 II Q4

Question 5.
\(\lim _{x \rightarrow 3}\left[\frac{x-3}{\sqrt{x-2}-\sqrt{4-x}}\right]\)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Miscellaneous Exercise 7 II Q5
Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Miscellaneous Exercise 7 II Q5.1

Question 6.
\(\lim _{x \rightarrow 4}\left[\frac{3-\sqrt{5+x}}{1-\sqrt{5-x}}\right]\)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Miscellaneous Exercise 7 II Q6

Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Miscellaneous Exercise 7

Question 7.
\(\lim _{x \rightarrow 0}\left[\frac{5^{x}-1}{x}\right]\)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Miscellaneous Exercise 7 II Q7

Question 8.
\(\lim _{x \rightarrow 0}\left(1+\frac{x}{5}\right)^{\frac{1}{x}}\)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Miscellaneous Exercise 7 II Q8

Question 9.
\(\lim _{x \rightarrow 0}\left[\frac{\log (1+9 x)}{x}\right]\)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Miscellaneous Exercise 7 II Q9

Question 10.
\(\lim _{x \rightarrow 0} \frac{(1-x)^{5}-1}{(1-x)^{3}-1}\)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Miscellaneous Exercise 7 II Q10

Question 11.
\(\lim _{x \rightarrow 0}\left[\frac{a^{x}+b^{x}+c^{x}-3}{x}\right]\)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Miscellaneous Exercise 7 II Q11

Question 12.
\(\lim _{x \rightarrow 0} \frac{e^{x}+e^{-x}-2}{x^{2}}\)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Miscellaneous Exercise 7 II Q12

Question 13.
\(\lim _{x \rightarrow 0}\left[\frac{x\left(6^{x}-3^{x}\right)}{\left(2^{x}-1\right) \cdot \log (1+x)}\right]\)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Miscellaneous Exercise 7 II Q13
Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Miscellaneous Exercise 7 II Q13.1

Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Miscellaneous Exercise 7

Question 14.
\(\lim _{x \rightarrow 0}\left[\frac{a^{3 x}-a^{2 x}-a^{x}+1}{x^{2}}\right]\)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Miscellaneous Exercise 7 II Q14

Question 15.
\(\lim _{x \rightarrow 0}\left[\frac{\left(5^{x}-1\right)^{2}}{x \cdot \log (1+x)}\right]\)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Miscellaneous Exercise 7 II Q15
Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Miscellaneous Exercise 7 II Q15.1

Question 16.
\(\lim _{x \rightarrow 0}\left[\frac{a^{4 x}-1}{b^{2 x}-1}\right]\)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Miscellaneous Exercise 7 II Q16

Question 17.
\(\lim _{x \rightarrow 0}\left[\frac{\log 100+\log (0.01+x)}{x}\right]\)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Miscellaneous Exercise 7 II Q17

Question 18.
\(\lim _{x \rightarrow 0}\left[\frac{\log (4-x)-\log (4+x)}{x}\right]\)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Miscellaneous Exercise 7 II Q18
Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Miscellaneous Exercise 7 II Q18.1

Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Miscellaneous Exercise 7

Question 19.
Evaluate the limit of the function if exist at x = 1 where,
\(f(x)= \begin{cases}7-4 x & x<1 \\ x^{2}+2 & x \geq 1\end{cases}\)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Miscellaneous Exercise 7 II Q19

11th Commerce Maths Digest Pdf

11th Commerce Maths 1 Chapter 9 Miscellaneous Exercise 9 Answers Maharashtra Board

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Std 11 Maths 1 Miscellaneous Exercise 9 Solutions Commerce Maths

I. Differentiate the following functions w.r.t.x.

Question 1.
x5
Solution:
Let y = x5
Differentiating w.r.t. x, we get
\(\frac{\mathrm{d} y}{\mathrm{~d} x}=\frac{\mathrm{d}}{\mathrm{d} x} x^{5}=5 x^{4}\)

Question 2.
x-2
Solution:
Let y = x-2
Differentiating w.r.t. x, we get
\(\frac{\mathrm{d} y}{\mathrm{~d} x}=\frac{\mathrm{d}}{\mathrm{d} x}\left(x^{-2}\right)=-2 x^{-3}=\frac{-2}{x^{3}}\)

Question 3.
√x
Solution:
Let y = √x
Differentiating w.r.t. x, we get
\(\frac{\mathrm{d} y}{\mathrm{~d} x}=\frac{\mathrm{d}}{\mathrm{d} x} \sqrt{x}=\frac{1}{2 \sqrt{x}}\)

Maharashtra Board 11th Commerce Maths Solutions Chapter 9 Differentiation Miscellaneous Exercise 9

Question 4.
x√x
Solution:
Let y = x√x
∴ y = \(x^{\frac{3}{2}}\)
Differentiating w.r.t. x, we get
\(\frac{\mathrm{d} y}{\mathrm{~d} x}=\frac{\mathrm{d}}{\mathrm{d} x} x^{\frac{3}{2}}=\frac{3}{2} x^{\frac{1}{2}}\)

Question 5.
\(\frac{1}{\sqrt{x}}\)
Solution:
Let y = \(\frac{1}{\sqrt{x}}\)
∴ y = \(x^{\frac{-1}{2}}\)
Differentiating w.r.t. x, we get
\(\frac{\mathrm{d} y}{\mathrm{~d} x}=\frac{-1}{2} x^{\frac{-3}{2}}=\frac{-1}{2 x^{\frac{3}{2}}}\)

Question 6.
7x
Solution:
Let y = 7x
Differentiating w.r.t. x, we get
\(\frac{\mathrm{d} y}{\mathrm{~d} x}=\frac{\mathrm{d}}{\mathrm{d} x} 7^{x}=7^{x} \log 7\)

II. Find \(\frac{d y}{d x}\) if

Question 1.
y = x2 + \(\frac{1}{x^{2}}\)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 9 Differentiation Miscellaneous Exercise 9 II Q1

Question 2.
y = (√x + 1)2
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 9 Differentiation Miscellaneous Exercise 9 II Q2

Maharashtra Board 11th Commerce Maths Solutions Chapter 9 Differentiation Miscellaneous Exercise 9

Question 3.
y = \(\left(\sqrt{x}+\frac{1}{\sqrt{x}}\right)^{2}\)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 9 Differentiation Miscellaneous Exercise 9 II Q3
Maharashtra Board 11th Commerce Maths Solutions Chapter 9 Differentiation Miscellaneous Exercise 9 II Q3.1

Question 4.
y = x3 – 2x2 + √x + 1
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 9 Differentiation Miscellaneous Exercise 9 II Q4

Question 5.
y = x2 + 2x – 1
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 9 Differentiation Miscellaneous Exercise 9 II Q5

Question 6.
y = (1 – x)(2 – x)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 9 Differentiation Miscellaneous Exercise 9 II Q6

Question 7.
y = \(\frac{1+x}{2+x}\)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 9 Differentiation Miscellaneous Exercise 9 II Q7
Maharashtra Board 11th Commerce Maths Solutions Chapter 9 Differentiation Miscellaneous Exercise 9 II Q7.1

Maharashtra Board 11th Commerce Maths Solutions Chapter 9 Differentiation Miscellaneous Exercise 9

Question 8.
y = \(\frac{(\log x+1)}{x}\)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 9 Differentiation Miscellaneous Exercise 9 II Q8

Question 9.
y = \(\frac{e^{x}}{\log x}\)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 9 Differentiation Miscellaneous Exercise 9 II Q9

Question 10.
y = x log x (x2 + 1)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 9 Differentiation Miscellaneous Exercise 9 II Q10

III. Solve the following:

Question 1.
The relation between price (P) and demand (D) of a cup of Tea is given by D = \(\frac{12}{P}\). Find
the rate at which the demand changes when the price is ₹ 2/-. Interpret the result.
Solution:
Demand, D = \(\frac{12}{P}\)
Rate of change of demand
Maharashtra Board 11th Commerce Maths Solutions Chapter 9 Differentiation Miscellaneous Exercise 9 III Q1
When price P = 2,
Rate of change of demand,
\(\left(\frac{\mathrm{dD}}{\mathrm{dP}}\right)_{\mathrm{P}=2}=\frac{-12}{(2)^{2}}=-3\)
∴ When the price is 2, the rate of change of demand is -3.
∴ Here, the rate of change of demand is negative demand would fall when the price becomes ₹ 2.

Question 2.
The demand (D) of biscuits at price P is given by D = \(\frac{64}{P^{3}}\), find the marginal demand
when the price is ₹ 4/-.
Solution:
Given demand D = \(\frac{64}{P^{3}}\)
Now, marginal demand
Maharashtra Board 11th Commerce Maths Solutions Chapter 9 Differentiation Miscellaneous Exercise 9 III Q2
When P = 4
Marginal demand
Maharashtra Board 11th Commerce Maths Solutions Chapter 9 Differentiation Miscellaneous Exercise 9 III Q2.1

Maharashtra Board 11th Commerce Maths Solutions Chapter 9 Differentiation Miscellaneous Exercise 9

Question 3.
The supply S of electric bulbs at price P is given by S = 2p3 + 5. Find the marginal supply when the price is ₹ 5/-. Interpret the result.
Solution:
Given, supply S = 2p3 + 5
Now, marginal supply
Maharashtra Board 11th Commerce Maths Solutions Chapter 9 Differentiation Miscellaneous Exercise 9 III Q3
∴ When p = 5
Marginal supply = \(\left(\frac{\mathrm{dS}}{\mathrm{dp}}\right)_{\mathrm{p}=5}\)
= 6(5)2
= 150
Here, the rate of change of supply with respect to the price is positive which indicates that the supply increases.

Question 4.
The total cost of producing x items is given by C = x2 + 4x + 4. Find the average cost and the marginal cost. What is the marginal cost when x = 7?
Solution:
Total cost C = x2 + 4x + 4
Now. Average cost = \(\frac{C}{x}=\frac{x^{2}+4 x+4}{x}\)
= x + 4 + \(\frac{4}{x}\)
and Marginal cost = \(\frac{\mathrm{dC}}{\mathrm{d} x}=\frac{\mathrm{d}}{\mathrm{d} x}\)(x2 + 4x + 4)
= \(\frac{\mathrm{d}}{\mathrm{d} x}\) (x2) + 4\(\frac{\mathrm{d}}{\mathrm{d} x}\) (x) + \(\frac{\mathrm{d}}{\mathrm{d} x}\) (4)
= 2x + 4(1) + 0
= 2x + 4
∴ When x = 7,
Marginal cost = \(\left(\frac{\mathrm{d} \mathrm{C}}{\mathrm{d} x}\right)_{x=7}\)
= 2(7) + 4
= 14 + 4
= 18

Question 5.
The demand D for a price P is given as D = \(\frac{27}{P}\), find the rate of change of demand when the price is ₹ 3/-.
Solution:
Demand, D = \(\frac{27}{P}\)
Rate of change of demand = \(\frac{dD}{dP}\)
Maharashtra Board 11th Commerce Maths Solutions Chapter 9 Differentiation Miscellaneous Exercise 9 III Q5
When price P = 3,
Rate of change of demand,
\(\left(\frac{\mathrm{dD}}{\mathrm{dP}}\right)_{\mathrm{P}=3}=\frac{-27}{(3)^{2}}=-3\)
∴ When price is 3, Rate of change of demand is -3.

Maharashtra Board 11th Commerce Maths Solutions Chapter 9 Differentiation Miscellaneous Exercise 9

Question 6.
If for a commodity; the price demand relation is given as D = \(\left(\frac{P+5}{P-1}\right)\). Find the marginal demand when price is ₹ 2/-
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 9 Differentiation Miscellaneous Exercise 9 III Q6

Question 7.
The price function P of a commodity is given as P = 20 + D – D2 where D is demand. Find the rate at which price (P) is changing when demand D = 3.
Solution:
Given, P = 20 + D – D2
Rate of change of price = \(\frac{dP}{dD}\)
= \(\frac{d}{dD}\)(20 + D – D2)
= 0 + 1 – 2D
= 1 – 2D
Rate of change of price at D = 3 is
\(\left(\frac{\mathrm{dP}}{\mathrm{dD}}\right)_{\mathrm{D}=3}\) = 1 – 2(3) = -5
∴ Price is changing at a rate of -5, when demand is 3.

Question 8.
If the total cost function is given by C = 5x3 + 2x2 + 1; find the average cost and the marginal cost when x = 4.
Solution:
Total cost function C = 5x3 + 2x2 + 1
Average cost = \(\frac{C}{x}\)
= \(\frac{5 x^{3}+2 x^{2}+1}{x}\)
= 5x2 + 2x + \(\frac{1}{x}\)
When x = 4,
Average cost = 5(4)2 + 2(4) + \(\frac{1}{4}\)
= 80 + 8 + \(\frac{1}{4}\)
= \(\frac{320+32+1}{4}\)
= \(\frac{353}{4}\)
Marginal cost = \(\frac{\mathrm{dC}}{\mathrm{d} x}\)
= \(\frac{d}{dx}\) (5x3 + 2x2 + 1)
= 5\(\frac{d}{dx}\) (x3) + 2 \(\frac{d}{dx}\) (x2) + \(\frac{d}{dx}\) (1)
= 5(3x2) + 2(2x) + 0
= 15x2 + 4x
When x = 4, marginal cost = \(\left(\frac{\mathrm{dC}}{\mathrm{d} x}\right)_{x=4}\)
= 15(4)2 + 4(4)
= 240 + 16
= 256
∴ The average cost and marginal cost at x = 4 are \(\frac{353}{4}\) and 256 respectively.

Maharashtra Board 11th Commerce Maths Solutions Chapter 9 Differentiation Miscellaneous Exercise 9

Question 9.
The supply S for a commodity at price P is given by S = P2 + 9P – 2. Find the marginal supply when the price is 7/-.
Solution:
Given, S = P2 + 9P – 2
Maharashtra Board 11th Commerce Maths Solutions Chapter 9 Differentiation Miscellaneous Exercise 9 III Q9
∴ The marginal supply is 23, at P = 7.

Question 10.
The cost of producing x articles is given by C = x2 + 15x + 81. Find the average cost and marginal cost functions. Find the marginal cost when x = 10. Find x for which the marginal cost equals the average cost.
Solution:
Given, cost C = x2 + 15x + 81
Maharashtra Board 11th Commerce Maths Solutions Chapter 9 Differentiation Miscellaneous Exercise 9 III Q10
If marginal cost = average cost, then
2x + 15 = x + 15 + \(\frac{81}{x}\)
∴ x = \(\frac{81}{x}\)
∴ x2 = 81
∴ x = 9 …..[∵ x > 0]

11th Commerce Maths Digest Pdf

11th Commerce Maths 1 Chapter 4 Exercise 4.1 Answers Maharashtra Board

Sequences and Series Class 11 Commerce Maths 1 Chapter 4 Exercise 4.1 Answers Maharashtra Board

Balbharati Maharashtra State Board 11th Commerce Maths Solution Book Pdf Chapter 4 Sequences and Series Ex 4.1 Questions and Answers.

Std 11 Maths 1 Exercise 4.1 Solutions Commerce Maths

Question 1.
Verify whether the following sequences are G.P. If so, write tn.
(i) 2, 6, 18, 54, ……
(ii) 1, -5, 25, -125, …….
(iii) \(\sqrt{5}, \frac{1}{\sqrt{5}}, \frac{1}{5 \sqrt{5}}, \frac{1}{25 \sqrt{5}}, \ldots\)
(iv) 3, 4, 5, 6, ……
(v) 7, 14, 21, 28, …..
Solution:
(i) 2, 6, 18, 54, …….
t1 = 2, t2 = 6, t3 = 18, t4 = 54, …..
Here, \(\frac{t_{2}}{t_{1}}=\frac{t_{3}}{t_{2}}=\frac{t_{4}}{t_{3}}=3\)
Since, the ratio of any two consecutive terms is a constant, the given sequence is a geometric progression.
Here, a = 2, r = 3
tn= arn-1
∴ tn = 2(3n-1)

Maharashtra Board 11th Commerce Maths Solutions Chapter 4 Sequences and Series Ex 4.1

(ii) 1, -5, 25, -125, ……
t1 = 1, t2 = -5, t3 = 25, t4 = -125, …..
Here, \(\frac{t_{2}}{t_{1}}=\frac{t_{3}}{t_{2}}=\frac{t_{4}}{t_{3}}=-5\)
Since, the ratio of any two consecutive terms is a constant, the given sequence is a geometric progression.
Here, a = 1, r = -5
tn = arn-1
∴ tn = (-5)n-1

(iii) \(\sqrt{5}, \frac{1}{\sqrt{5}}, \frac{1}{5 \sqrt{5}}, \frac{1}{25 \sqrt{5}}, \ldots\)
Maharashtra Board 11th Commerce Maths Solutions Chapter 4 Sequences and Series Ex 4.1 Q1
Since, the ratio of any two consecutive terms is a constant, the given sequence is a geometric progression.
Maharashtra Board 11th Commerce Maths Solutions Chapter 4 Sequences and Series Ex 4.1 Q1.1

(iv) 3, 4, 5, 6,……
t1 = 3, t2 = 4, t3 = 5, t4 = 6, …..
Here, \(\frac{\mathrm{t}_{2}}{\mathrm{t}_{1}}=\frac{4}{3}, \frac{\mathrm{t}_{3}}{\mathrm{t}_{2}}=\frac{5}{4}, \frac{\mathrm{t}_{4}}{\mathrm{t}_{3}}=\frac{6}{5}\)
Since, \(\frac{t_{2}}{t_{1}} \neq \frac{t_{3}}{t_{2}} \neq \frac{t_{4}}{t_{3}}\)
∴ the given sequence is not a geometric progression.

(v) 7, 14, 21, 28, …..
t1 = 7, t2 = 14, t3 = 21, t4 = 28, …..
Here, \(\frac{t_{2}}{t_{1}}=2, \frac{t_{3}}{t_{2}}=\frac{3}{2}, \frac{t_{4}}{t_{3}}=\frac{4}{3}\)
Since, \(\frac{\mathrm{t}_{2}}{\mathrm{t}_{1}} \neq \frac{\mathrm{t}_{3}}{\mathrm{t}_{2}} \neq \frac{\mathrm{t}_{4}}{\mathrm{t}_{3}}\)
∴ the given sequence is not a geometric progression.

Maharashtra Board 11th Commerce Maths Solutions Chapter 4 Sequences and Series Ex 4.1

Question 2.
For the G.P.,
(i) if r = \(\frac{1}{3}\), a = 9, find t7.
(ii) if a = \(\frac{7}{243}\), r = \(\frac{1}{3}\), find t3.
(iii) if a = 7, r = -3, find t6.
(iv) if a = \(\frac{2}{3}\), t6 = 162, find r.
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 4 Sequences and Series Ex 4.1 Q2
Maharashtra Board 11th Commerce Maths Solutions Chapter 4 Sequences and Series Ex 4.1 Q2.1

Question 3.
Which term of the G. P. 5, 25, 125, 625, ….. is 510?
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 4 Sequences and Series Ex 4.1 Q3

Question 4.
For what values of x, \(\frac{4}{3}\), x, \(\frac{4}{27}\) are in G. P.?
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 4 Sequences and Series Ex 4.1 Q4

Question 5.
If for a sequence, \(t_{n}=\frac{5^{n-3}}{2^{n-3}}\), show that the sequence is a G. P. Find its first term and the common ratio.
Solution:
The sequence (tn) is a G.P., if \(\frac{t_{n}}{t_{n-1}}\) = constant, for all n ∈ N
Maharashtra Board 11th Commerce Maths Solutions Chapter 4 Sequences and Series Ex 4.1 Q5
∴ the sequence is a G. P. with common ratio \(\frac{5}{2}\)
First term, t1 = \(\frac{5^{\mathrm{l}-3}}{2^{1-3}}=\frac{2^{2}}{5^{2}}=\frac{4}{25}\)

Maharashtra Board 11th Commerce Maths Solutions Chapter 4 Sequences and Series Ex 4.1

Question 6.
Find three numbers in G. P. such that their sum is 21 and sum of their squares is 189.
Solution:
Let the three numbers in G. P. be \(\frac{a}{\mathrm{r}}\), a, ar.
According to the first condition,
Maharashtra Board 11th Commerce Maths Solutions Chapter 4 Sequences and Series Ex 4.1 Q6
Maharashtra Board 11th Commerce Maths Solutions Chapter 4 Sequences and Series Ex 4.1 Q6.1
Maharashtra Board 11th Commerce Maths Solutions Chapter 4 Sequences and Series Ex 4.1 Q6.2
∴ the three numbers are 12, 6, 3 or 3, 6, 12.
Check:
First condition:
12, 6, 3 are in G.P. with r = \(\frac{1}{2}\)
12 + 6 + 3 = 21
Second condition:
122 + 62 + 32 = 144 + 36 + 9 = 189
Thus, both the conditions are satisfied.

Question 7.
Find four numbers in G. P. such that sum of the middle two numbers is \(\frac{10}{3}\) and their product is 1.
Solution:
Let the four numbers in G.P. be \(\frac{a}{r^{3}}, \frac{a}{r}, a r, a r^{3}\).
According to the second condition,
\(\frac{\mathrm{a}}{\mathrm{r}^{3}}\left(\frac{\mathrm{a}}{\mathrm{r}}\right)(\mathrm{ar})\left(\mathrm{ar}^{3}\right)=1\)
∴ a4 = 1
∴ a = 1
According to the first condition,
Maharashtra Board 11th Commerce Maths Solutions Chapter 4 Sequences and Series Ex 4.1 Q7

Question 8.
Find five numbers in G. P. such that their product is 1024 and the fifth term is square of the third term.
Solution:
Let the five numbers in G. P. be
\(\frac{a}{r^{2}}, \frac{a}{r}, a, a r, a r^{2}\)
According to the given conditions,
Maharashtra Board 11th Commerce Maths Solutions Chapter 4 Sequences and Series Ex 4.1 Q8
When a = 4, r = -2
\(\frac{a}{r^{2}}\) = 1, \(\frac{a}{r}\) = -2, a = 4, ar = -8, ar2 = 16
∴ the five numbers in G.P. are 1, 2, 4, 8, 16 or 1, -2, 4, -8, 16.

Maharashtra Board 11th Commerce Maths Solutions Chapter 4 Sequences and Series Ex 4.1

Question 9.
The fifth term of a G. P. is x, eighth term of the G. P. is y and eleventh term of the G. P. is z. Verify whether y2 = xz.
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 4 Sequences and Series Ex 4.1 Q9

Question 10.
If p, q, r, s are in G. P., show that p + q, q + r, r + s are also in G.P.
Solution:
p, q, r, s are in G.P.
Maharashtra Board 11th Commerce Maths Solutions Chapter 4 Sequences and Series Ex 4.1 Q10
∴ p + q, q + r, r + s are in G.P.

11th Commerce Maths Digest Pdf

11th Commerce Maths 1 Chapter 2 Miscellaneous Exercise 2 Answers Maharashtra Board

Functions Class 11 Commerce Maths 1 Chapter 2 Miscellaneous Exercise 2 Answers Maharashtra Board

Balbharati Maharashtra State Board 11th Commerce Maths Solution Book Pdf Chapter 2 Functions Miscellaneous Exercise 2 Questions and Answers.

Std 11 Maths 1 Miscellaneous Exercise 2 Solutions Commerce Maths

Question 1.
Which of the following relations are functions? If it is a function determine its domain and range.
(i) {(2, 1), (4, 2), (6, 3), (8, 4), (10, 5) (12, 6), (14, 7)}
(ii) {(0, 0), (1, 1), (1, -1), (4, 2), (4, -2), (9, 3), (9, -3), (16, 4), (16, -4)}
(iii) {(1, 1), (3, 1), (5, 2)}
Solution:
(i) {(2, 1), (4, 2), (6, 3), (8, 4), (10, 5) (12, 6), (14, 7)}
Maharashtra Board 11th Commerce Maths Solutions Chapter 2 Functions Miscellaneous Exercise 2 Q1
Every element of set A has been assigned a unique element in set B.
∴ Given relation is a function.
Domain = {2, 4, 6, 8, 10, 12, 14},
Range = {1, 2, 3, 4, 5, 6, 7}

(ii) {(0, 0), (1, 1), (1, -1), (4, 2), (4, -2), (9, 3), (9, -3), (16, 4), (16, -4)}
∴ (1, 1), (1, -1) ∈ the relation
∴ Given relation is not a function.
As element 1 of the domain has not been assigned a unique element of co-domain.

(iii) {(1, 1), (3, 1), (5, 2)}
Maharashtra Board 11th Commerce Maths Solutions Chapter 2 Functions Miscellaneous Exercise 2 Q1.1
Every element of set A has been assigned a unique element in set B.
∴ Given relation is a function.
Domain = {1, 3, 5}, Range = {1, 2}

Maharashtra Board 11th Commerce Maths Solutions Chapter 2 Functions Miscellaneous Exercise 2

Question 2.
A function f: R → R defined by f(x) = \(\frac{3 x}{5}\) + 2, x ∈ R. Show that f is one-one and onto. Hence, find f-1.
Solution:
f: R → R defined by f(x) = \(\frac{3 x}{5}\) + 2
First we have to prove that f is one-one function for that we have to prove if
f(x1) = f(x2) then x1 = x2
Here f(x) = \(\frac{3 x}{5}\) + 2
Let f(x1) = f(x2)
∴ \(\frac{3 x_{1}}{5}+2=\frac{3 x_{2}}{5}+2\)
∴ \(\frac{3 x_{1}}{5}=\frac{3 x_{2}}{5}\)
∴ x1 = x2
∴ f is a one-one function.
Now, we have to prove that f is an onto function.
Let y ∈ R be such that
y = f(x)
∴ y = \(\frac{3 x}{5}\) + 2
∴ y – 2 = \(\frac{3 x}{5}\)
∴ x = \(\frac{5(y-2)}{3}\) ∈ R
∴ for any y ∈ co-domain R, there exist an element x = \(\frac{5(y-2)}{3}\) ∈ domain R such that f(x) = y
∴ f is an onto function.
∴ f is one-one onto function.
∴ f-1 exists.
∴ \(\mathrm{f}^{-1}(y)=\frac{5(y-2)}{3}\)
∴ \(f^{-1}(x)=\frac{5(x-2)}{3}\)

Question 3.
A function f is defined as follows:
f(x) = 4x + 5, for -4 ≤ x < 0. Find the values of f(-1), f(-2), f(0), if they exist.
Solution:
f(x) = 4x + 5, -4 ≤ x < 0
f(-1) = 4(-1) + 5 = -4 + 5 = 1
f(-2) = 4(-2) + 5 = -8 + 5 = -3
x = 0 ∉ domain of f
∴ f(0) does not exist.

Maharashtra Board 11th Commerce Maths Solutions Chapter 2 Functions Miscellaneous Exercise 2

Question 4.
A function f is defined as follows:
f(x) = 5 – x for 0 ≤ x ≤ 4. Find the value of x such that f(x) = 3.
Solution:
f(x) = 5 – x
f(x) = 3
∴ 5 – x = 3
∴ x = 5 – 3 = 2

Question 5.
If f(x) = 3x2 – 5x + 7, find f(x – 1).
Solution:
f(x) = 3x2 – 5x + 7
∴ f(x – 1) = 3(x – 1)2 – 5(x – 1) + 7
= 3(x2 – 2x + 1) – 5(x – 1) + 7
= 3x2 – 6x + 3 – 5x + 5 + 7
= 3x2 – 11x + 15

Question 6.
If f(x) = 3x + a and f(1) = 7, find a and f(4).
Solution:
f(x) = 3x + a,
f(1) = 7
∴ 3(1) + a = 7
∴ a = 7 – 3 = 4
∴ f(x) = 3x + 4
∴ f(4) = 3(4) + 4
= 12 + 4
= 16

Question 7.
If f(x) = ax2 + bx + 2 and f(1) = 3, f(4) = 42, find a and b.
Solution:
f(x) = ax2 + bx + 2
f(1) = 3
∴ a(1)2 + b(1) + 2 = 3
∴ a + b = 1 …….(i)
f(4) = 42
∴ a(4)2 + b(4) + 2 = 42
∴ 16a + 4b = 40
Dividing by 4, we get
4a + b = 10 ……….(ii)
Solving (i) and (ii), we get
a = 3, b = -2

Maharashtra Board 11th Commerce Maths Solutions Chapter 2 Functions Miscellaneous Exercise 2

Question 8.
If f(x) = \(\frac{2 x-1}{5 x-2}, x \neq \frac{2}{5}\), verify whether (fof)(x) = x
Solution:
(fof)(x) = f(f(x))
Maharashtra Board 11th Commerce Maths Solutions Chapter 2 Functions Miscellaneous Exercise 2 Q8

Question 9.
If f(x) = \(\frac{x+3}{4 x-5}\), g(x) = \(\frac{3+5 x}{4 x-1}\), then verify that (fog)(x) = x.
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 2 Functions Miscellaneous Exercise 2 Q9

11th Commerce Maths Digest Pdf

11th Commerce Maths 1 Chapter 6 Exercise 6.2 Answers Maharashtra Board

Determinants Class 11 Commerce Maths 1 Chapter 6 Exercise 6.2 Answers Maharashtra Board

Balbharati Maharashtra State Board 11th Commerce Maths Solution Book Pdf Chapter 6 Determinants Ex 6.2 Questions and Answers.

Std 11 Maths 1 Exercise 6.2 Solutions Commerce Maths

Question 1.
Without expanding, evaluate the following determinants.
(i) \(\left|\begin{array}{lll}
1 & a & b+c \\
1 & b & c+a \\
1 & c & a+b
\end{array}\right|\)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 6 Determinants Ex 6.2 Q1(i)

(ii) \(\left|\begin{array}{ccc}
2 & 3 & 4 \\
5 & 6 & 8 \\
6 x & 9 x & 12 x
\end{array}\right|\)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 6 Determinants Ex 6.2 Q1(ii)

(iii) \(\left|\begin{array}{lll}
2 & 7 & 65 \\
3 & 8 & 75 \\
5 & 9 & 86
\end{array}\right|\)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 6 Determinants Ex 6.2 Q1(iii)

Question 2.
Using properties of determinants, show that \(\left|\begin{array}{ccc}
a+b & a & b \\
a & a+c & c \\
b & c & b+c
\end{array}\right|\) = 4abc
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 6 Determinants Ex 6.2 Q2

Maharashtra Board 11th Commerce Maths Solutions Chapter 6 Determinants Ex 6.2

Question 3.
Solve the following equation.
\(\left|\begin{array}{ccc}
x+2 & x+6 & x-1 \\
x+6 & x-1 & x+2 \\
x-1 & x+2 & x+6
\end{array}\right|=0\)
Solution:
\(\left|\begin{array}{ccc}
x+2 & x+6 & x-1 \\
x+6 & x-1 & x+2 \\
x-1 & x+2 & x+6
\end{array}\right|=0\)
Applying R2 → R2 – R1 and R3 → R3 – R1, we get
\(\left|\begin{array}{ccc}
x+2 & x+6 & x-1 \\
4 & -7 & 3 \\
-3 & -4 & 7
\end{array}\right|=0\)
∴ (x + 2)(-49 + 12) – (x + 6)(28 + 9) + (x – 1)(-16 – 21) = 0
∴ (x + 2) (-37) – (x + 6) (37) + (x – 1) (-37) = 0
∴ -37(x + 2 + x + 6 + x – 1) = 0
∴ 3x + 7 = 0
∴ x = \(\frac{-7}{3}\)

Question 4.
If \(\left|\begin{array}{lll}
4+x & 4-x & 4-x \\
4-x & 4+x & 4-x \\
4-x & 4-x & 4+x
\end{array}\right|=0\), then find the values of x.
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 6 Determinants Ex 6.2 Q4
∴ (12 – x)[1(4x2 – 0) – (4 – x)(0 – 0) + (4 – x)(0 – 0)] = 0
∴ (12 – x)(4x2) = 0
∴ x2(12 – x) = 0
∴ x = 0 or 12 – x = 0
∴ x = 0 or x = 12

Question 5.
Without expanding determinants, show that
\(\left|\begin{array}{ccc}
1 & 3 & 6 \\
6 & 1 & 4 \\
3 & 7 & 12
\end{array}\right|+4\left|\begin{array}{lll}
2 & 3 & 3 \\
2 & 1 & 2 \\
1 & 7 & 6
\end{array}\right|=10\left|\begin{array}{lll}
1 & 2 & 1 \\
3 & 1 & 7 \\
3 & 2 & 6
\end{array}\right|\)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 6 Determinants Ex 6.2 Q5
Maharashtra Board 11th Commerce Maths Solutions Chapter 6 Determinants Ex 6.2 Q5.1

Question 6.
Without expanding determinants, find the value of
(i) \(\left|\begin{array}{lll}
10 & 57 & 107 \\
12 & 64 & 124 \\
15 & 78 & 153
\end{array}\right|\)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 6 Determinants Ex 6.2 Q6(i)

(ii) \(\left|\begin{array}{lll}
2014 & 2017 & 1 \\
2020 & 2023 & 1 \\
2023 & 2026 & 1
\end{array}\right|\)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 6 Determinants Ex 6.2 Q6(ii)

Maharashtra Board 11th Commerce Maths Solutions Chapter 6 Determinants Ex 6.2

Question 7.
Without expanding determinants, prove that
(i) \(\left|\begin{array}{lll}
a_{1} & b_{1} & c_{1} \\
a_{2} & b_{2} & c_{2} \\
a_{3} & b_{3} & c_{3}
\end{array}\right|=\left|\begin{array}{lll}
b_{1} & c_{1} & a_{1} \\
b_{2} & c_{2} & a_{2} \\
b_{3} & c_{3} & a_{3}
\end{array}\right|=\left|\begin{array}{lll}
c_{1} & a_{1} & b_{1} \\
c_{2} & a_{2} & b_{2} \\
c_{3} & a_{3} & b_{3}
\end{array}\right|\)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 6 Determinants Ex 6.2 Q7(i)
Maharashtra Board 11th Commerce Maths Solutions Chapter 6 Determinants Ex 6.2 Q7(i).1

(ii) \(\left|\begin{array}{lll}
1 & y z & y+z \\
1 & z x & z+x \\
1 & x y & x+y
\end{array}\right|=\left|\begin{array}{lll}
1 & x & x^{2} \\
1 & y & y^{2} \\
1 & z & z^{2}
\end{array}\right|\)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 6 Determinants Ex 6.2 Q7(ii)
In 1st determinant, taking (x + y + z) common from C3 and in 2nd determinant, taking \(\frac{1}{x}, \frac{1}{y}, \frac{1}{z}\) common from R1, R2, R3 respectively, we get
Maharashtra Board 11th Commerce Maths Solutions Chapter 6 Determinants Ex 6.2 Q7(ii).1

11th Commerce Maths Digest Pdf

11th Commerce Maths 1 Chapter 2 Exercise 2.1 Answers Maharashtra Board

Functions Class 11 Commerce Maths 1 Chapter 2 Exercise 2.1 Answers Maharashtra Board

Balbharati Maharashtra State Board 11th Commerce Maths Solution Book Pdf Chapter 2 Functions Ex 2.1 Questions and Answers.

Std 11 Maths 1 Exercise 2.1 Solutions Commerce Maths

Question 1.
Check if the following relations are functions.
Maharashtra Board 11th Commerce Maths Solutions Chapter 2 Functions Ex 2.1 Q1
Maharashtra Board 11th Commerce Maths Solutions Chapter 2 Functions Ex 2.1 Q1.1
Solution:
(a) Yes
Reason: Every element of set A has been assigned a unique element in set B.

(b) No
Reason: An element of set A has been assigned more than one element from set B.

(c) No
Reason: Not every element of set A has been assigned an image from set B.

Maharashtra Board 11th Commerce Maths Solutions Chapter 2 Functions Ex 2.1

Question 2.
Which sets of ordered pairs represent functions from A = {1, 2, 3, 4} to B = {-1, 0, 1, 2, 3}? Justify.
(i) {(1, 0), (3, 3), (2, -1), (4, 1), (2, 2)}
(ii) {(1, 2), (2, -1), (3, 1), (4, 3)}
(iii) {(1, 3), (4, 1), (2, 2)}
(iv) {(1, 1), (2, 1), (3, 1), (4, 1)}
Solution:
(i) {(1, 0), (3, 3), (2, -1), (4, 1), (2, 2)} does not represent a function.
Reason: (2, -1) and (2, 2) show that element 2 ∈ A has been assigned two images -1 and 2 from set B.

(ii) {(1, 2), (2, -1), (3, 1), (4, 3)} represents a function.
Reason: Every element of set A has a unique image in set B.

(iii) {(1, 3), (4, 1), (2, 2)} does not represent a function.
Reason: 3 ∈ A does not have an image in set B.

(iv) {(1, 1), (2, 1), (3, 1), (4, 1)} represents a function
Reason: Every element of set A has been assigned a unique image in set B.

Question 3.
If f(m) = m2 – 3m + 1, find
(i) f(0)
(ii) f(-3)
(iii) f(\(\frac{1}{2}\))
(iv) f(x + 1)
(v) f(-x)
Solution:
f(m) = m2 – 3m + 1
(i) f(0) = 02 – 3(0) + 1 = 1

(ii) f(-3) = (-3)2 – 3(-3) + 1
= 9 + 9 + 1
= 19

(iii) \(f\left(\frac{1}{2}\right)=\left(\frac{1}{2}\right)^{2}-3\left(\frac{1}{2}\right)+1\)
= \(\frac{1}{4}-\frac{3}{2}+1\)
= \(\frac{1-6+4}{4}\)
= \(-\frac{1}{4}\)

(iv) f(x + 1) = (x + 1)2 – 3(x + 1) + 1
= x2 + 2x + 1 – 3x – 3 + 1
= x2 – x – 1

(v) f(-x) = (-x)2 – 3(-x) + 1 = x2 + 3x + 1

Maharashtra Board 11th Commerce Maths Solutions Chapter 2 Functions Ex 2.1

Question 4.
Find x, if g(x) = 0 where
(i) g(x) = \(\frac{5 x-6}{7}\)
(ii) g(x) = \(\frac{18-2 x^{2}}{7}\)
(iii) g(x) = 6x2 + x – 2
Solution:
(i) g(x) = \(\frac{5 x-6}{7}\)
g(x) = 0
∴ \(\frac{5 x-6}{7}\) = 0
∴ 5x – 6 = 0
∴ x = \(\frac{6}{5}\)

(ii) g(x) = \(\frac{18-2 x^{2}}{7}\)
g(x) = 0
∴ \(\frac{18-2 x^{2}}{7}\) = 0
∴ 18 – 2x2 = 0
∴ x2 = 9
∴ x = ±3

(iii) g(x) = 6x2 + x – 2
g(x) = 0
∴ 6x2 + x – 2 = 0
∴ 6x2 + 4x – 3x – 2 = 0
∴ 2x(3x + 2) – 1(3x + 2) = 0
∴ (2x – 1)(3x + 2) = 0
∴ 2x – 1 = 0 or 3x + 2 = 0
∴ x = \(\frac{1}{2}\) or x = \(\frac{-2}{3}\)

Question 5.
Find x, if f(x) = g(x) where f(x) = x4 + 2x2, g(x) = 11x2.
Solution:
f(x) = x4 + 2x2, g(x) = 11x2
f(x) = g(x)
∴ x4 + 2x2 = 11x2
∴ x4 – 9x2 = 0
∴ x2(x2 – 9) = 0
∴ x2 = 0 or x2 – 9 = 0
∴ x = 0 or x2 = 9
∴ x = 0 or x = ±3

Maharashtra Board 11th Commerce Maths Solutions Chapter 2 Functions Ex 2.1

Question 6.
If f(x) = \(\begin{cases}x^{2}+3, & x \leq 2 \\ 5 x+7, & x>2\end{cases}\), then find
(i) f(3)
(ii) f(2)
(iii) f(0)
Solution:
f(x) = x2 + 3, x ≤ 2
= 5x + 7, x > 2
(i) f(3) = 5(3) + 7 = 15 + 7 = 22
(ii) f(2) = 22 + 3 = 4 + 3 = 7
(iii) f(0) = 02 + 3 = 3

Question 7.
If f(x) = \(\left\{\begin{array}{cl}
4 x-2, & x \leq-3 \\
5, & -3<x<3 \\
x^{2}, & x \geq 3
\end{array}\right.\), then fmd
(i) f(-4)
(ii) f(-3)
(iii) f(1)
(iv) f(5)
Solution:
f(x) = 4x – 2, x ≤ -3
= 5, -3 < x < 3
= x2, x ≥ 3
(i) f(-4) = 4(-4) – 2 = -16 – 2 = -18
(ii) f(-3) = 4(-3) – 2 = -12 – 2 = -14
(iii) f(1) = 5
(iv) f(5) = 52 = 25

Maharashtra Board 11th Commerce Maths Solutions Chapter 2 Functions Ex 2.1

Question 8.
If f(x) = 3x + 5, g(x) = 6x – 1, then find
(i) (f + g)(x)
(ii) (f – g)(2)
(iii) (fg)(3)
(iv) \(\left(\frac{\mathbf{f}}{\mathbf{g}}\right)(x)\) and its domain
Solution:
f(x) = 3x + 5, g(x) = 6x – 1
(i) (f + g)(x) = f(x) + g(x)
= 3x + 5 + 6x – 1
= 9x + 4

(ii) (f – g) (2) = f(2) – g(2)
= [3(2) + 5] – [6(2) – 1]
= 6 + 5 – 12 + 1
= 0

(iii) (fg)(3) = f(3) g(3)
= [3(3) + 5] [6(3) – 1]
= (14) (17)
= 238

(iv) \(\left(\frac{\mathrm{f}}{\mathrm{g}}\right) x=\frac{\mathrm{f}(x)}{\mathrm{g}(x)}=\frac{3 x+5}{6 x-1}, x \neq \frac{1}{6}\)
Domain = R – {\(\frac{1}{6}\)}

Question 9.
If f(x) = 2x2 + 3, g(x) = 5x – 2, then find
(i) fog
(ii) gof
(iii) fof
(iv) gog
Solution:
f(x) = 2x2 + 3, g(x) = 5x – 2
(i) (fog)(x) = f(g(x))
= f(5x – 2)
= 2(5x – 2)2 + 3
= 2(25x2 – 20x + 4) + 3
= 50x2 – 40x + 8 + 3
= 50x2 – 40x + 11

(ii) (gof)(x) = g(f(x))
= g(2x2 + 3)
= 5(2x2 + 3) – 2
= 10x2 + 15 – 2
= 10x2 + 13

Maharashtra Board 11th Commerce Maths Solutions Chapter 2 Functions Ex 2.1

(iii) (fof)(x) = f(f(x))
= f(2x2 + 3)
= 2(2x2 + 3)2 + 3
= 2(4x4 + 12x2 + 9) + 3
= 8x4 + 24x2 + 18 + 3
= 8x4 + 24x2 + 21

(iv) (gog)(x) = g(g(x))
= g(5x – 2)
= 5(5x – 2) – 2
= 25x – 10 – 2
= 25x – 12

11th Commerce Maths Digest Pdf

11th Commerce Maths 1 Chapter 7 Exercise 7.4 Answers Maharashtra Board

Limits Class 11 Commerce Maths 1 Chapter 7 Exercise 7.4 Answers Maharashtra Board

Balbharati Maharashtra State Board 11th Commerce Maths Solution Book Pdf Chapter 7 Limits Ex 7.4 Questions and Answers.

Std 11 Maths 1 Exercise 7.4 Solutions Commerce Maths

I. Evaluate the following:

Question 1.
\(\lim _{x \rightarrow 0}\left[\frac{9^{x}-5^{x}}{4^{x}-1}\right]\)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Ex 7.4 Q1(i)

Question 2.
\(\lim _{x \rightarrow 0}\left[\frac{5^{x}+3^{x}-2^{x}-1}{x}\right]\)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Ex 7.4 Q1(ii)

Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Ex 7.4

Question 3.
\(\lim _{x \rightarrow 0}\left[\frac{\log (2+x)-\log (2-x)}{x}\right]\)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Ex 7.4 Q1(iii)
Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Ex 7.4 Q1(iii).1

II. Evaluate the following:

Question 1.
\(\lim _{x \rightarrow 0}\left[\frac{3^{x}+3^{-x}-2}{x^{2}}\right]\)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Ex 7.4 Q2(i)

Question 2.
\(\lim _{x \rightarrow 0}\left[\frac{3+x}{3-x}\right]^{\frac{1}{x}}\)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Ex 7.4 Q2(ii)

Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Ex 7.4

Question 3.
\(\lim _{x \rightarrow 0}\left[\frac{\log (3-x)-\log (3+x)}{x}\right]\)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Ex 7.4 Q2(iii)
Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Ex 7.4 Q2(iii).1

III. Evaluate the following:

Question 1.
\(\lim _{x \rightarrow 0}\left[\frac{a^{3 x}-b^{2 x}}{\log (1+4 x)}\right]\)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Ex 7.4 Q3(i)
Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Ex 7.4 Q3(i).1

Question 2.
\(\lim _{x \rightarrow 0}\left[\frac{\left(2^{x}-1\right)^{2}}{\left(3^{x}-1\right) \cdot \log (1+x)}\right]\)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Ex 7.4 Q3(ii)
Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Ex 7.4 Q3(ii).1

Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Ex 7.4

Question 3.
\(\lim _{x \rightarrow 0}\left[\frac{15^{x}-5^{x}-3^{x}+1}{x^{2}}\right]\)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Ex 7.4 Q3(iii)

Question 4.
\(\lim _{x \rightarrow 2}\left[\frac{3^{\frac{x}{2}}-3}{3^{x}-9}\right]\)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Ex 7.4 Q3(iv)
Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Ex 7.4 Q3(iv).1

IV. Evaluate the following:

Question 1.
\(\lim _{x \rightarrow 0}\left[\frac{(25)^{x}-2(5)^{x}+1}{x^{2}}\right]\)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Ex 7.4 Q4(i)

Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Ex 7.4

Question 2.
\(\lim _{x \rightarrow 0}\left[\frac{(49)^{x}-2(35)^{x}+(25)^{x}}{x^{2}}\right]\)
Solution:
Maharashtra Board 11th Commerce Maths Solutions Chapter 7 Limits Ex 7.4 Q4(ii)

11th Commerce Maths Digest Pdf

11th Commerce Maths 1 Chapter 1 Miscellaneous Exercise 1 Answers Maharashtra Board

Sets and Relations Class 11 Commerce Maths 1 Chapter 1 Miscellaneous Exercise 1 Answers Maharashtra Board

Balbharati Maharashtra State Board 11th Commerce Maths Solution Book Pdf Chapter 1 Sets and Relations Miscellaneous Exercise 1 Questions and Answers.

Std 11 Maths 1 Miscellaneous Exercise 1 Solutions Commerce Maths

Question 1.
Write the following sets in set builder form:
(i) {10, 20, 30, 40, 50}
(ii) {a, e, i, o, u}
(iii) {Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday}
Solution:
(i) Let A = {10, 20, 30, 40, 50}
∴ A = {x / x = 10n, n ∈ N and n ≤ 5}

(ii) Let B = {a, e, i, o, u}
∴ B = {x / x is a vowel of English alphabets}

(iii) Let C = {Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday}
∴ C = {x / x represents days of a week}

Maharashtra Board 11th Commerce Maths Solutions Chapter 1 Sets and Relations Miscellaneous Exercise 1

Question 2.
If U = {x / x ∈ N, 1 ≤ x ≤ 12}, A = {1, 4, 7, 10}, B = {2, 4, 6, 7, 11}, C = {3, 5, 8, 9, 12}.
Write the sets
(i) A ∪ B
(ii) B ∩ C
(iii) A – B
(iv) B – C
(v) A ∪ B ∪ C
(vi) A ∩ (B ∪ C)
Solution:
U = {x / x ∈ N, 1 ≤ x ≤ 12} = {1, 2, 3, …., 12}
A = {1, 4, 7, 10}, B = {2, 4, 6, 7, 11}, C = {3, 5, 8, 9, 12}
(i) A ∪ B = {1, 2, 4, 6, 7, 10, 11}

(ii) B ∩ C = { }

(iii) A – B = {1, 10}

(iv) B – C = {2, 4, 6, 7, 11}

(v) A ∪ B ∪ C = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12}

(vi) B ∪ C = {2, 3, 4, 5, 6, 7, 8, 9, 11, 12}
∴ A ∩ (B ∪ C) = {4, 7}

Question 3.
In a survey of 425 students in a school, it was found that 115 drink apple juice, 160 drink orange juice, and 80 drink both apple as well as orange juice. How many drinks neither apple juice nor orange juice?
Solution:
Let A = set of students who drink apple juice
B = set of students who drink orange juice
X = set of all students
∴ n(X) = 425, n(A) = 115, n(B) = 160, n(A ∩ B) = 80
Maharashtra Board 11th Commerce Maths Solutions Chapter 1 Sets and Relations Miscellaneous Exercise 1 Q3
No. of students who neither drink apple juice nor orange juice
n(A’ ∩ B’) = n(A ∪ B)’
= n(X) – n(A ∪ B)
= 425 – [n(A) + n(B) – n(A ∩ B)]
= 425 – (115 + 160 – 80)
= 230

Maharashtra Board 11th Commerce Maths Solutions Chapter 1 Sets and Relations Miscellaneous Exercise 1

Question 4.
In a school, there are 20 teachers who teach Mathematics or Physics. of these, 12 teach Mathematics and 4 teach both Physics and Mathematics. How many teachers teach Physics?
Solution:
Let A = set of teachers who teach Mathematics
B = set of teachers who teach Physics
n(A ∪ B) = 20, n(A) = 12, n(A ∩ B) = 4
Maharashtra Board 11th Commerce Maths Solutions Chapter 1 Sets and Relations Miscellaneous Exercise 1 Q4
Since, n(A ∪ B) = n(A) + n(B) – n(A ∩ B)
∴ 20 = 12 + n(B) – 4
∴ n(B) = 12
∴ Number of teachers who teach physics = 12

Question 5.
(i) If A = {1, 2, 3} and B = {2, 4}, state the elements of A × A, A × B, B × A, B × B, (A × B) ∩ (B × A).
(ii) If A = {-1, 1}, find A × A × A.
Solution:
(i) A = {1, 2, 3} and B = {2, 4}
A × A = {(1, 1), (1, 2), (1, 3), (2, 1), (2, 2), (2, 3), (3, 1), (3, 2), (3, 3)}
A × B = {(1, 2), (1, 4), (2, 2), (2, 4), (3, 2), (3, 4)}
B × A = {(2, 1), (2, 2), (2, 3), (4, 1), (4, 2), (4, 3)}
B × B = {(2, 2), (2, 4), (4, 2), (4, 4)}
(A × B) ∩ (B × A) = {(2, 2)}

(ii) A = {-1, 1}
∴ A × A × A = {(-1, -1, -1), (-1, -1, 1), (-1, 1, -1), (-1, 1, 1), (1, -1, -1), (1, -1, 1), (1, 1, -1),(1, 1, 1)}

Question 6.
If A = {1, 2, 3}, B = {4, 5, 6}, which of the following are relations from A to B.
(i) R1 = {(1, 4), (1, 5), (1, 6)}
(ii) R2 = {(1, 5), (2, 4), (3, 6)}
(iii) R3 = {(1, 4), (1, 5), (3, 6), (2, 6), (3, 4)}
(iv) R4 = {(4, 2), (2, 6), (5, 1), (2, 4)}
Solution:
A = {1, 2, 3}, B = {4, 5, 6}
∴ A × B = {(1, 4), (1, 5), (1, 6), (2, 4), (2, 5), (2, 6), (3, 4), (3, 5), (3, 6)}
(i) R1 = {(1, 4), (1, 5), (1, 6)}
Since, R1 ⊆ A × B
∴ R1 is a relation from A to B.

(ii) R2 = {(1, 5), (2, 4), (3, 6)}
Since, R2 ⊆ A × B
∴ R2 is a relation from A to B.

(iii) R3 = {(1, 4), (1, 5), (3, 6), (2, 6), (3, 4)}
Since, R3 ⊆ A × B
∴ R3 is a relation from A to B.

(iv) R4 = {(4,2), (2, 6), (5,1), (2, 4)}
Since, (4, 2) ∈ R4, but (4, 2) ∉ A × B
∴ R4 ⊄ A × B
∴ R4 is not a relation from A to B.

Maharashtra Board 11th Commerce Maths Solutions Chapter 1 Sets and Relations Miscellaneous Exercise 1

Question 7.
Determine the domain and range of the following relation.
R = {(a, b) / a ∈ N, a < 5, b = 4}
Solution:
R = {(a, b) / a ∈ N, a < 5, b = 4}
∴ Domain (R) = {a / a ∈ N, a < 5} = {1, 2, 3, 4}
Range (R) = {b / b = 4} = {4}

11th Commerce Maths Digest Pdf