如果(x+1)2+|y+2|=0,求代数式5xy-3/2x3y2-4xy+1/2y2x3-1/2xy-3x3y2-y2x3的值.

题目

如果(x+1)2+|y+2|=0,求代数式5xy-3/2x3y2-4xy+1/2y2x3-1/2xy-3x3y2-y2x3的值.

答案

由(x+1)2+|y+2|=0可求出x=-1 y=-2
5xy-3/2x^3y^2-4xy+1/2y^2x^3-1/2xy-3x^3y^2-y^2x^3
=-5x^3y^2+1/2xy
当x=-1 y=-2时
原式=……代入
=21