{(x+y)²-(x-y)²}÷(-4xy)= (3xy-y)÷y=还有(x+y)²÷(x+y)

问题描述:

{(x+y)²-(x-y)²}÷(-4xy)= (3xy-y)÷y=
还有(x+y)²÷(x+y)