∫x²e^x²dx=(1/2)∫xe^x²d(x²)=(1/2)∫xd(e^x²)=(1/2)xe^x²-(1/2)∫e^x²dx=(1/2)xe^x²-(√π/4)*erfi(x)+c其中erfi(x)是虚误差函数
(1/2)∫xde^x^2=(1/2)xe^2-(1/2)∫e^x^2dx.