已知,M（x+y)(x-y)={2XY-Y^2/（x+y)(x-y)}+1,则M=
问题描述：
已知,M（x+y)(x-y)={2XY-Y^2/（x+y)(x-y)}+1,则M=
答
M（x+y)(x-y)={2XY-Y²/（x+y)(x-y)}+1
=[2XY-Y²+x²-y²]/[（x+y)(x-y)],
M=[x²+2xy-2y²]/[（x+y)²(x-y)²],