化简求值:[(x-2y)2-4y2+2xy]÷2x,其中x=1,y=2.
问题描述:
化简求值:[(x-2y)2-4y2+2xy]÷2x,其中x=1,y=2.
答
∵x=1,y=2,
∴[(x-2y)2-4y2+2xy]÷2x=(x2-4xy+4y2-4y2+2xy)÷2x
=(x2-2xy)÷2x
=
x-y1 2
=
×1-21 2
=-
.3 2