Integral Calculus Question 480

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

[RPET 2002]

Options:

A) $ \frac{1}{2}{{\tan }^{-1}}(\sqrt{x})+c $

B) $ {{\tan }^{-1}}(\sqrt{x})+c $

C) $ 2{{\tan }^{-1}}(\sqrt{x})+c $

D) None of these

Show Answer

Answer:

Correct Answer: B

Solution:

$ I=\int{\frac{dx}{2\sqrt{x}(1+x)}} $ . Put $ \sqrt{x},=t $ Þ $ \frac{1}{2\sqrt{x}}dx=dt $
$ \therefore I=\int{\frac{dt}{1+t^{2}}}={{\tan }^{-1}}t+c $ $ ={{\tan }^{-1}}(\sqrt{x})+c $ .