Integral Calculus Question 381

Question: $ \int_{{}}^{{}}{\frac{1}{x{{(\log x)}^{2}}}}\ dx= $

Options:

A) $ \frac{1}{\log x}+c $

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

C) $ \log \log x+c $

D) $ -\log \log x+c $

Show Answer

Answer:

Correct Answer: B

Solution:

Put $ \log x=t\Rightarrow \frac{1}{x},dx=dt, $ then $ \int_{{}}^{{}}{\frac{1}{x{{(\log x)}^{2}}},dx}=\int_{{}}^{{}}{\frac{1}{t^{2}},dt}=-\frac{1}{t}+c=-\frac{1}{\log x}+c. $