Integral Calculus Question 495

Question: $ \int_{{}}^{{}}{\frac{x}{\sqrt{4-x^{4}}}dx}= $

[Roorkee 1976]

Options:

A) $ {{\cos }^{-1}}\frac{x^{2}}{2} $

B) $ \frac{1}{2}{{\cos }^{-1}}\frac{x^{2}}{2} $

C) $ {{\sin }^{-1}}\frac{x^{2}}{2} $

D) $ \frac{1}{2}{{\sin }^{-1}}\frac{x^{2}}{2} $

Show Answer

Answer:

Correct Answer: D

Solution:

$ \int_{{}}^{{}}{\frac{x}{\sqrt{4-x^{4}}}},dx=\int_{{}}^{{}}{\frac{x}{\sqrt{2^{2}-{{(x^{2})}^{2}}}}},dx $ Putting $ x^{2}=t\Rightarrow 2x,dx=dt, $ we get the required integral $ =\frac{1}{2}{{\sin }^{-1}}\frac{x^{2}}{2} $ .