设z=ln(1-x+y)+x2y,求∂2z/∂y∂x．

设z=ln(1-x+y)+x2y,求∂2z/∂y∂x．
【正确答案】：∂z/∂y=1/(1-x+y)+x2，∂2z/∂y∂x=1/(1-x+y)2+2x．