{(x+y)²-(x-y)²}÷(-4xy)= (3xy-y)÷y=

问题描述:

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

{(x+y)²-(x-y)²}÷(-4xy)=[x^2+2xy+y^2-(x^2-2xy+y^2]/(-4xy)=4xy/(-4xy)=-1
(3xy-y)÷y=3xy/y-y/y=3x-1还有(x+y)²÷(x+y)(x+y)^2/(x+y)=x+y告诉我(x+y)²÷(x+y)怎么直接得x+y的(x+y)^2÷(x+y)=(x+y)^(2-1)=x+y