Yash Jain11 Years agoThe question is ∫ tan-1[ 1/(x2+x+1) ] dxThis can be written as ∫ tan-1[ {(x+1)-x} / {1+x(x+1)} ] dxFrom the formula of tan-1[ (m-n) / 1+mn ], We get∫ tan-1(x+1) – tan-1x dxI guess now you can proceed on your own.