已知:x/y=1/2,求x^2+2xy+y^2/x^2-xy-2y^2的值
问题描述：
已知:x/y=1/2,求x^2+2xy+y^2/x^2-xy-2y^2的值
答
x/y=1/2
y=2x
(x²+2xy+y²)/(x²-xy-2y²)
=(x+y)²/(x-2y(x+y)
=(x+y)/(x-2y)
=3x/(-3x)
=-1