{(x²+y²)-(x-y)+2y(x-y)}/4y
问题描述:
{(x²+y²)-(x-y)+2y(x-y)}/4y
答
{(x²+y²)-(x-y)²+2y(x-y)}/4y
=(x²+y²-x²+2xy-y²+2xy-2y²)/4y
=(4xy-2y²)/4y
=x-y/2