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
答
[(x-y)2+(x-y)(x+y)]÷x,
=(x2-2xy+y2+x2-y2)÷x,
=(2x2-2xy)÷x,
=2x-2y,
当x=-1,y=
,原式=2×(-1)-2×1 2
=-3.1 2