化简分式计算①、(x+y)*x^2/x^2-y^2+y^2/x-y-(2x^2y-2xy^2)/(x^2-2xy+y^2)②、m/m-n-n/m+n+2mn/m^2-n^2

①、(x+y)*x^2/x^2-y^2+y^2/x-y-(2x^2y-2xy^2)/(x^2-2xy+y^2)
=x^2/(x-y)+y^2/(x-y)-2xy(x-y)/(x-y)^2
=(x^2+y^2)/(x-y)-2xy/(x-y)
=(x^2+y^2-2xy)/(x-y)
=x-y
②、m/m-n-n/m+n+2mn/m^2-n^2
={m(m+n)-n(m-n)}/(m^2-n^2)+2mn/(m^2-n^2)
=(m^2+n^2+2mn)/(m+n)(m-n)
=(m+n)/(m-n)

①、(x+y)*x^2/x^2-y^2+y^2/x-y-(2x^2y-2xy^2)/(x^2-2xy+y^2)
=x^2+y^2/x-y - 2xy（x-y）/（x-y）^2
=x^2- 2xy+y^2/x-y
=x-y
②、m/m-n-n/m+n+2mn/m^2-n^2
=m^2+n^2/（m+n）（m-n）+ 2mn/（m+n）（m-n）
=m+n/m-n

①、(x+y)*x^2/x^2-y^2+y^2/x-y-(2x^2y-2xy^2)/(x^2-2xy+y^2)
=x^2/(x-y)+y^2/(x-y)-2xy(x-y)/(x-y)^2
=(x^2+y^2)/(x-y)-2xy/(x-y)
=(x^2+y^2-2xy)/(x-y)
=x-y
②、m/m-n-n/m+n+2mn/m^2-n^2
={m(m+n)-n(m-n)}/(m^2-n^2)+2mn/(m^2-n^2)
=(m^2+n^2+2mn)/(m+n)(m-n)
=(m+n)/(m-n)