两个数学计算.

问题描述:

两个数学计算.
a/b-(a-b)/b=
x^2+xy/(x-y)÷xy/(x-y)

a/b-(a-b)/b=(a-a+b)/b=b/b=1
(x^2+xy)/(x-y)÷xy/(x-y)
=(x^2+xy)/xy
=(x+y)/y