$\int e^{\tan^{-1}x}(1+x+x^2)d(\cot^{-1}x)=$
Answer & explanation
Correct answer: option 3
$I=-\int e^{\tan^{-1}x}(1+x+x^2).\frac{1}{1+x^2}dx$
$=-\int e^{\tan^{-1}x}dx-\int\frac{e^{\tan^{-1}x}}{1+x^2}.dx$
$=-\int e^{\tan^{-1}x}dx-\{e^{\tan^{-1}x}.x-\int e^{\tan^{-1}x}.1\,dx\}+c$
$=-xe^{\tan^{-1}x}+c$