The value of $\int\limits_{-1}^1|\tan^{-1}x| dx$ is: |
$\frac{\pi}{2}-\log_e2$ $\frac{\pi}{2}+\log_e2$ $\frac{\pi-1-\log_e2}{2}$ $\frac{\pi-1+\log_e2}{2}$ |
$\frac{\pi}{2}-\log_e2$ |
The correct answer is Option (1) → $\frac{\pi}{2}-\log_e2$ $I=\int|\tan^{-1}x| dx$ $⇒I=\int\limits_{x<0}-\tan^{-1}x\,dx+\int\limits_{x≥0}-\tan^{-1}x\,dx$ and, $\int\limits_{x≥0}\tan^{-1}x\,dx=x\tan^{-1}x-\frac{1}{2}\log|1+x^2|+C$ $∴I=\left\{\begin{matrix}-x\tan^{-1}x+\frac{1}{2}\log|1+x^2|+C,&x<0\\x\tan^{-1}x-\frac{1}{2}\log|1+x^2|+C&x≥0\end{matrix}\right.$ $∴\int\limits_{-1}^1|\tan^{-1}x|=\frac{\pi}{2}-\log_e2$ |