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

问题描述:

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

=[(x²-2xy+y²)-(x²-4y²)]/y
=(x²-2xy+y²-x²+4y²)/y
=(5y²-2xy)/ y
=5y-2x