Target Exam

CUET

Subject

-- Mathematics - Section B1

Chapter

Indefinite Integration

Question:

$\int \frac{1}{x(\log x)^{2}} dx$ is equal to:

Options:

$2 \log (\log x) + c$

$-\frac{1}{\log x} + c$

$\frac{(\log x)^{3}}{3} + c$

$-\frac{3}{(\log)^{3}} + c$

Correct Answer:

$-\frac{1}{\log x} + c$

Explanation:

The correct answer is Option (2) → $-\frac{1}{\log x} + c$

Let $I = \int \frac{1}{x(\log x)^{2}} dx$

$\log x = t ⇒\frac{1}{x} dx = dt$

$I = \int \frac{dt}{t^{2}} = -\frac{1}{t} + c$

Thus, $I = -\frac{1}{\log x} + c$