y=(1+x²)arctanx y'=((1+x²)arctanx )'=(1+x²)'arctanx+(1+x²)(arctanx)'=2xarctanx+(1+x²)(1/(1+x²))=2xarctanx+1y''=(y')'=(2xarctanx+1)'=(2xarctanx)'=(2x)'arctanx+2x(arctanx)'...