已知m+n=3,mn=2/3,求m^3n-m^2n^2+nm^3怎么写
问题描述：
已知m+n=3,mn=2/3,求m^3n-m^2n^2+nm^3怎么写
答
m+n=3
平方
m²+2mn+n²=9
m²+n²
=9-2mn
=9-4/3
=23/3
所以原式=mn(m²+n²)+(mn)²
=46/9+4/9
=50/9