Question
The value of $$\int {{e^{{{\tan }^{ - 1}}x}}\frac{{\left( {1 + x + {x^2}} \right)}}{{1 + {x^2}}}} dx$$ is :
A.
$$x{e^{{{\tan }^{ - 1}}}}x + c$$
B.
$${\tan ^{ - 1}}x + C$$
C.
$${e^{{{\tan }^{ - 1}}x}} + 2x + C$$
D.
none of these
Answer :
$$x{e^{{{\tan }^{ - 1}}}}x + c$$
Solution :
$$\eqalign{
& {\text{Put }}x = \tan \,\theta \Rightarrow dx = {\sec ^2}\theta \,d\theta \cr
& I = \int {{e^\theta }} \frac{{1 + \tan \,\theta + {{\tan }^2}\theta }}{{1 + {{\tan }^2}\theta }}.{\sec ^2}\theta \,d\theta \cr
& \,\,\,\,\, = \int {{e^\theta }} \left( {\tan \,\theta + {{\sec }^2}\theta } \right)d\theta \cr
& \,\,\,\,\, = {e^\theta }\tan \,\theta + c \cr
& \,\,\,\,\, = x{e^{{{\tan }^{ - 1}}x}} + c \cr} $$