Integral Calculus Question 443

Question: $ \int_{{}}^{{}}{\frac{e^{x}\ dx}{\sqrt{1-e^{2x}}}=} $

Options:

A) $ {{\cos }^{-1}}(e^{x})+c $

B) $ -{{\cos }^{-1}}(e^{x})+c $

C) $ {{\cos }^{-1}}(e^{2x})+c $

D) $ \sqrt{1-e^{2x}}+c $

Show Answer

Answer:

Correct Answer: B

Solution:

Put $ e^{x}=t\Rightarrow e^{x}dx=dt, $ then $ \int_{{}}^{{}}{\frac{e^{x}dx}{\sqrt{1-e^{2x}}},=\int_{{}}^{{}}{\frac{dt}{\sqrt{1-t^{2}}}=-{{\cos }^{-1}}t+c}}=-{{\cos }^{-1}}(e^{x})+c $ .