已知x+y=3,xy=1,求代数式①x2y+xy2;②x2+y2的值.

问题描述:

已知x+y=3,xy=1,求代数式①x2y+xy2;②x2+y2的值.

①x2y+xy2
=xy(x+y)
=1×3
=3;
②x2+y2
=(x+y)2-2xy
=32-2×1
=7.