∫arctanx/(1+x²)^(3/2)dx
=∫arctanxd[x/√(x²+1)],分部积分法,∫dx/(1+x²)^(3/2)=x/√(x²+1)
=[x/√(x²+1)]arctanx-∫x/√(x²+1)d(arctanx),(arcanx)'=1/(x²+1)
=x*arctanx/√(x²+1)-∫x/(x²+1)^(3/2)dx
=x*arctanx/√(x²+1)-(1/2)∫d(x²+1)/(x²+1)^(3/2)
=x*arctanx/√(x²+1)-(1/2)*(x²+1)^(-3/2+1)/(-3/2+1)+C
=x*arctanx/√(x²+1)-(1/2)(-2)(x²+1)^(-1/2)+C
=x*arctanx/√(x²+1)+1/√(x²+1)+C
=(x*arctanx+1)/√(x²+1)+C