Definite Integration Question 239

Question: The value of the integral $ \int _{-1}^{1}{\frac{d}{dx}( {{\tan }^{-1}}\frac{1}{x} )}dx $ is

Options:

A) $ \frac{\pi }{2} $

B) $ \frac{\pi }{4} $

C) $ -\frac{\pi }{2} $

D) None of these

Show Answer

Answer:

Correct Answer: C

Solution:

$ \int _{-1}^{1}{\frac{d}{dx}}( {{\tan }^{-1}}\frac{1}{x} )dx=-2[{{\tan }^{-1}}(x)]_0^{1}=-\frac{\pi }{2} $ .