Target Exam

CUET

Subject

-- Mathematics - Section A

Chapter

Indefinite Integration

Question:

The integral of the function $\frac{1}{9-4x^2}$ is:

Options:

$\frac{1}{22}\log_e\left|\frac{3+x}{3-x}\right|+C$, where C is an arbitrary constant

$\frac{1}{12}\log_e\left|\frac{3+2x}{3-2x}\right|+C$, where C is an arbitrary constant

$\frac{1}{2}\log_e\left|\frac{7+x}{7-x}\right|+C$, where C is an arbitrary constant

$\frac{1}{12}\log_e\left|\frac{3-2x}{3+2x}\right|+C$, where C is an arbitrary constant

Correct Answer:

$\frac{1}{12}\log_e\left|\frac{3+2x}{3-2x}\right|+C$, where C is an arbitrary constant

Explanation:

The correct answer is Option (2) → $\frac{1}{12}\log_e\left|\frac{3+2x}{3-2x}\right|+C$, where C is an arbitrary constant

$\int\frac{1}{9-4x^2}dx=\frac{1}{4}\int\frac{1}{(\frac{3}{2})^2-x^2}dx$

$=\frac{1}{4}×\frac{2}{2×3}\log\left|\frac{\frac{3}{2}+x}{\frac{3}{2}-x}\right|+C$

$=\frac{1}{12}\log\left|\frac{3+2x}{3-2x}\right|+C$