先化简,后求值[(x-y)3(3次方)+(x2-y2)(x-y)]/(-2x),其中x=3,y=-2
问题描述:
先化简,后求值[(x-y)3(3次方)+(x2-y2)(x-y)]/(-2x),其中x=3,y=-2
答
[(x-y)3(3次方)+(x2-y2)(x-y)]/(-2x)
=(x-y)^2[(x-y)+(x+y)]/(-2x)
=(x-y)^2[2x]/(-2x)
=-(x-y)^2
=-(3+2)^2=-25