(xy-x^2)-(x2-2xy+y^2)/xy×(x^2-y^2)/x^2 -xy-y^2

问题描述:

(xy-x^2)-(x2-2xy+y^2)/xy×(x^2-y^2)/x^2 -xy-y^2

(xy-x^2) ÷ (x2-2xy+y^2)/xy×(x^2-y^2)/x^2
=-x(x-y)×xy/(x-y)²×(x+y)(x-y)/x²
=-y(x+y)
=-xy-y²