MCQ
If $I =\int_{1 / e}^{ e }|\log x| \frac{ d x}{x^2}$, then I is equal to
  • A
    2
  • B
    $\frac{2}{ e }$
  • $2\left(1-\frac{1}{ e }\right)$
  • D
    $0$

Answer

Correct option: C.
$2\left(1-\frac{1}{ e }\right)$
(C)
Since $|\log x|=-\log x$, if $\frac{1}{ e }<x<1$
$=\log x$, if $1<x< e$
$\therefore I =\int_{1 / e }^1 \frac{(-\log x)}{x^2} d x+\int_1^{ e } \frac{\log x}{x^2} d x$
$=-\left[-\frac{\log x}{x}-\frac{1}{x}\right]_{1 / e }^1+\left[-\frac{\log x}{x}-\frac{1}{x}\right]_1^{ e } \\ =\left[0+1-\left(\frac{\log \frac{1}{ e }}{\frac{1}{ e }}+\frac{1}{\frac{1}{ e }}\right)\right]-\left[\frac{\log e }{ e }+\frac{1}{ e }-(0+1)\right] \\ =1-(- e + e )-\left(\frac{2}{ e }-1\right) \\ =2-\frac{2}{ e }=2\left(1-\frac{1}{ e }\right)$

Need a full question paper?

Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.

Start Generating Free