Practicing Success

Target Exam

CUET

Subject

-- Mathematics - Section A

Chapter

# Integration: Evaluation of indefinite integrals

Question:

Match List-I with List-II

List-I

List-II

 A. $\int \frac{d x}{\sqrt{9 x^2-16}}$

 I. $\frac{1}{3} \sin ^{-1} \frac{3 x}{4}+C$

 B. $\int \frac{d x}{\sqrt{16-9 x^2}}$

 II. $\log \left(e^x+1\right)+C$

 C. $\int \frac{e^{2 \log _e x}+1}{e^{2 \log _e x}-1} d x$ 

 III. $\frac{1}{3} \log _e\left|3 x+\sqrt{9 x^2-16}\right|+C$ 

 D. $\int \frac{1}{1+e^{-x}} d x$

 IV. $x+\log _e\left|\frac{x-1}{x+1}\right|+C$ 

Choose the correct answer from the options given below :

Options:

A-I, B-III, C-II, D-IV

A-I, B-III, C-IV, D-II

A-III, B-I, C-IV, D-II

A-III, B-I, C-II, D-IV

Correct Answer:

A-III, B-I, C-IV, D-II

Explanation:

A. $\int \frac{d x}{\sqrt{9 x^2-16}} = \frac{1}{3} \int \frac{d x}{\sqrt{x^2-(\frac{4}{3})^2}}$

$\Rightarrow I =\frac{1}{3} \ln \left|x+\sqrt{x^2-\frac{16}{9}}\right|+C$

$\Rightarrow I=\frac{1}{3} \ln \left|3 x+\sqrt{9 x^2-16}\right|+C$           →         III

B. $\int \frac{d x}{\sqrt{16-9 x^2}} = \int \frac{d x}{\sqrt{4^2-(3 x)^2}}=\frac{1}{3} \sin ^{-1} \frac{3 x}{4}+C$              →             I

C. $\int \frac{e^{2 \log  x}+1}{e^{2 \log  x}-1} d x = \int \frac{x^2+1}{x^2 - 1}dx$

$= \int \frac{x^2-1}{x^2-1} + \frac{2}{x^2-1}dx = \int 1 + \frac{2}{x^2-1} dx = x+\frac{2}{2} \log _e\left|\frac{x-1}{x+1}\right|+C$              →              IV

D. $\int \frac{1}{1+e^{-x}} d x = \int \frac{e^x}{e^x+1} d x = \log \left|e^x+1\right|+C$              →           II