-a-b+2b^2/a+b

问题描述:

-a-b+2b^2/a+b

原式=-(a+b)+2b²/(a+b)
=[-(a+b)²+2b²]/(a+b)
=(-a²-2ab-b²+2b²)/(a+b)
=(-a²-2ab+b²)/(a+b)