NCERT Solutions
Class 12 - Mathematics Part-2 - Chapter 7: INTEGRALS
Exercise 7.5

Question. 1

Integrate the rational function \(\dfrac{x}{(x+1)(x+2)}\).

Answer:

\(\log\left|\dfrac{(x+2)^2}{x+1}\right|+C\)

Question. 2

Integrate the rational function \(\dfrac{1}{x^2-9}\).

Answer:

\(\dfrac{1}{6}\log\left|\dfrac{x-3}{x+3}\right|+C\)

Question. 3

Integrate the rational function \(\dfrac{3x-1}{(x-1)(x-2)(x-3)}\).

Answer:

\(\log|x-1|-5\log|x-2|+4\log|x-3|+C\)

Question. 4

Integrate the rational function \(\dfrac{x}{(x-1)(x-2)(x-3)}\).

Answer:

\(\dfrac{1}{2}\log|x-1|-2\log|x-2|+\dfrac{3}{2}\log|x-3|+C\)

Question. 5

Integrate the rational function \(\dfrac{2x}{x^2+3x+2}\).

Answer:

\(4\log|x+2|-2\log|x+1|+C\)

Question. 6

Integrate the rational function \(\dfrac{1-x^2}{x(1-2x)}\).

Answer:

\(\dfrac{x}{2}+\log|x|-\dfrac{3}{4}\log|1-2x|+C\)

Question. 7

Integrate the rational function \(\dfrac{x}{(x^2+1)(x-1)}\).

Answer:

\(\dfrac{1}{2}\log|x-1|-\dfrac{1}{4}\log(x^2+1)+\dfrac{1}{2}\tan^{-1}x+C\)

Question. 8

Integrate the rational function \(\dfrac{x}{(x-1)^2(x+2)}\).

Answer:

\(\dfrac{2}{9}\log\left|\dfrac{x-1}{x+2}\right|-\dfrac{1}{3(x-1)}+C\)

Question. 9

Integrate the rational function \(\dfrac{3x+5}{x^3-x^2-x+1}\).

Answer:

\(\dfrac{1}{2}\log\left|\dfrac{x+1}{x-1}\right|-\dfrac{4}{x-1}+C\)

Question. 10

Integrate the rational function \(\dfrac{2x-3}{(x^2-1)(2x+3)}\).

Answer:

\(\dfrac{5}{2}\log|x+1|-\dfrac{1}{10}\log|x-1|-\dfrac{12}{5}\log|2x+3|+C\)

Question. 11

Integrate the rational function \(\dfrac{5x}{(x+1)(x^2-4)}\).

Answer:

\(\dfrac{5}{3}\log|x+1|-\dfrac{5}{2}\log|x+2|+\dfrac{5}{6}\log|x-2|+C\)

Question. 12

Integrate the rational function \(\dfrac{x^3+x+1}{x^2-1}\).

Answer:

\(\dfrac{x^2}{2}+\dfrac{1}{2}\log|x+1|+\dfrac{3}{2}\log|x-1|+C\)

Question. 13

Integrate the rational function \(\dfrac{2}{(1-x)(1+x^2)}\).

Answer:

\(-\log|x-1|+\dfrac{1}{2}\log(1+x^2)+\tan^{-1}x+C\)

Question. 14

Integrate the rational function \(\dfrac{3x-1}{(x+2)^2}\).

Answer:

\(3\log|x+2|+\dfrac{7}{x+2}+C\)

Question. 15

Integrate the rational function \(\dfrac{1}{x^4-1}\).

Answer:

\(\dfrac{1}{4}\log\left|\dfrac{x-1}{x+1}\right|-\dfrac{1}{2}\tan^{-1}x+C\)

Question. 16

Integrate the rational function \(\dfrac{1}{x(x^n+1)}\).

Hint: multiply numerator and denominator by \(x^{n-1}\) and put \(x^n=t\).

Answer:

\(\dfrac{1}{n}\log\left|\dfrac{x^n}{x^n+1}\right|+C\)

Question. 17

Integrate \(\dfrac{\cos x}{(1-\sin x)(2-\sin x)}\).

Hint: Put \(\sin x=t\).

Answer:

\(\log\left|\dfrac{2-\sin x}{1-\sin x}\right|+C\)

Question. 18

Integrate the rational function \(\dfrac{(x^2+1)(x^2+2)}{(x^2+3)(x^2+4)}\).

Answer:

\(x+\dfrac{2}{\sqrt{3}}\tan^{-1}\left(\dfrac{x}{\sqrt{3}}\right)-3\tan^{-1}\left(\dfrac{x}{2}\right)+C\)

Question. 19

Integrate the rational function \(\dfrac{2x}{(x^2+1)(x^2+3)}\).

Answer:

\(\dfrac{1}{2}\log\left(\dfrac{x^2+1}{x^2+3}\right)+C\)

Question. 20

Integrate the rational function \(\dfrac{1}{x(x^4-1)}\).

Answer:

\(\dfrac{1}{4}\log\left|\dfrac{x^4-1}{x^4}\right|+C\)

Question. 21

Integrate \(\dfrac{1}{e^x-1}\).

Hint: Put \(e^x=t\).

Answer:

\(\log\left(\dfrac{e^x-1}{e^x}\right)+C\)

Question. 22

Choose the correct answer:

\(\displaystyle \int \dfrac{x\,dx}{(x-1)(x-2)}\) equals

(A) \(\log\left|\dfrac{(x-1)^2}{x-2}\right|+C\)

(B) \(\log\left|\dfrac{(x-2)^2}{x-1}\right|+C\)

(C) \(\log\left|\left(\dfrac{x-1}{x-2}\right)^2\right|+C\)

(D) \(\log|(x-1)(x-2)|+C\)

Answer:

B

Question. 23

Choose the correct answer:

\(\displaystyle \int \dfrac{dx}{x(x^2+1)}\) equals

(A) \(\log|x|-\dfrac{1}{2}\log(x^2+1)+C\)

(B) \(\log|x|+\dfrac{1}{2}\log(x^2+1)+C\)

(C) \(-\log|x|+\dfrac{1}{2}\log(x^2+1)+C\)

(D) \(\dfrac{1}{2}\log|x|+\log(x^2+1)+C\)

Answer:

A

NCERT Solutions Class 12 – Mathematics Part-2 – Chapter 7: INTEGRALS – Exercise 7.5 | Detailed Answers