已知2x+y=4,求代数式[(x+y)2-(x-y)2-2y(x-1/2y)]÷4y的值.
问题描述:
已知2x+y=4,求代数式[(x+y)2-(x-y)2-2y(x-
y)]÷4y的值. 1 2
答
原式=[x2+y2+2xy-x2-y2+2xy-2xy+y2]÷4y
=(2xy+y2)÷4y
=
(2x+y)1 4
=
×41 4
=1.