Integral Calculus Question 423

Question: The value of $ \int_{{}}^{{}}{e^{x}{{\sec }^{2}}(e^{x})\ dx} $ is

Options:

A) $ \tan (e^{x})+k $

B) $ \tan (e^{x})\ .\ e+k $

C) $ e^{x}\tan x+k $

D) $ \frac{\tan (e^{x})}{e^{x}}+k $

Show Answer

Answer:

Correct Answer: A

Solution:

$ I=\int_{{}}^{{}}{e^{x}{{\sec }^{2}}(e^{x}),dx} $ . Put $ e^{x}=t\Rightarrow e^{x}dx=dt $
$ \therefore ,I=\int_{{}}^{{}}{{{\sec }^{2}}t,dt=\tan t+k=\tan (e^{x})+k} $ .