[(2x+y)^2+(y+2x)(y-2x)-2y(4x-y)]/4y

问题描述:

[(2x+y)^2+(y+2x)(y-2x)-2y(4x-y)]/4y

=(4x*x+4xy+y*y+y*y-4x*x-8xy+2y*y)/4y
=(4y*y-4xy)/4y
=y-x