Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Indefinite Integration

Question:

Find $\int \frac{1}{x(1+x^2)} dx$.

Options:

$\ln|x| + \frac{1}{2} \ln(1+x^2) + C$

$\tan^{-1}x - \ln|x| + C$

$\ln|x| - \frac{1}{2} \ln(1+x^2) + C$

$\frac{1}{2} \ln \left| \frac{x^2}{1+x^2} \right| + C$

Correct Answer:

$\ln|x| - \frac{1}{2} \ln(1+x^2) + C$

Explanation:

The correct answer is Option (3) → $\ln|x| - \frac{1}{2} \ln(1+x^2) + C$

$I = \int \frac{1}{x(1+x^2)} dx = \int \left( \frac{1}{x} - \frac{x}{1+x^2} \right) dx$

$= \log |x| - \frac{1}{2} \ln(1+x^2) + C$