∫y^2*e^-ydy=怎么算啊
问题描述：
∫y^2*e^-ydy=怎么算啊
答
原式=-y²e^(-y)+2∫ye^(-y)dy (应用分部积分法)
=-y²e^(-y)-2ye^(-y)+2∫e^(-y)dy (应用分部积分法)
=-y²e^(-y)-2ye^(-y)-2e^(-y)+C (C是任意常数)
=C-(y²+2y+2)e^(-y).