先化简,再求值:[(x-y)2+(x-y)(x+y)]÷x,其中x=-1,y=1/2.

问题描述:

先化简,再求值:[(x-y)2+(x-y)(x+y)]÷x,其中x=-1,y=

1
2

[(x-y)2+(x-y)(x+y)]÷x,
=(x2-2xy+y2+x2-y2)÷x,
=(2x2-2xy)÷x,
=2x-2y,
当x=-1,y=

1
2
,原式=2×(-1)-2×
1
2
=-3.