Question

计算：（x-y）分之2+y分之x-x分之1

Answer 1

通分:
[2xy+x(x-y)x-(x-y)y]/[xy(x-y)]
=(2xy+x³-x²y-xy+y²)/[xy(x-y)]
=(xy+x³-x²y+y²)/[xy(x-y)]

Answer 2

解：
2/(x-y)+x/y-1/x
=2xy/[xy(x-y)]+(x^2)(x-y)/[xy(x-y)]-y(x-y)/[xy(x-y)]
=[2xy+(x^2)(x-y)-y(x-y)]/[xy(x-y)]
=[2xy+x^3-(x^2)y-xy+y^2]/[xy(x-y)]
=[x^3-x(x-1)y+y^2]/[xy(x-y)]