Question

（1）xy减y方分之2Xy方乘xy分之X方减y方 （2） （x方减y方） 除以x加y分之xy减y方

Answer 1

xy减y方分之2Xy方乘xy分之X方减y方
=2xy²/(xy-y²)*(x²-y²)/xy
=2xy²/y(x-y)*(x-y)(x+y)/xy
=2x(x+y)
=2x²+2xy

（x方减y方） 除以x加y分之xy减y方
(x²-y²)÷(xy-y²)/(x+y)
=(x-y)(x+y)*(x+y)/x(x-y)
=(x+y)²/x