Q1)
f(x)= x^2/(x sinx+ cosx)^2
This is a tricky problem.Here we cannot go for any substitution as there is x term as well as xsinx+ cosx term.
We can write x2=(xsinx+cosx)(xsinx)-(sinx-xcosx)(xcosx)
So f(x)=(xsinx+cosx)(xsinx)-(sinx-xcosx)(xcosx)/(x sinx+ cosx)2
Now if we observe clearly f(x) is nothing but d/dx((sinx-xcosx)/(xsinx+cosx))
So 
f(x)dx=(sinx-xcosx)/(xsinx+cosx)+c
Moderation Team
![[Post New]](/templates/default/images/icon_minipost_new.gif){kind=icon}
![[Up]](/templates/default/images/icon_up.gif "[Up]"){kind=icon}
272
