分式x+y分之x-y与(x+y)²分之x²-y²相等吗?
问题描述:
分式x+y分之x-y与(x+y)²分之x²-y²相等吗?
答
相等.理由如下;
∵(x-y)/(x+y)
∴x+y≠0
∴(x-y)/(x+y)=[(x-y)(x+y)]/[(x+y)(x+y)]=(x²-y²)/(x+y)²