5(xy-x²)÷(xy/x²-2xy+y²)的-1次方×x²-y²/x² 其中x=1/2,y=-2/3

5(xy-x²)÷(xy/x²-2xy+y²)的-1次方×x²-y²/x² 其中x=1/2,y=-2/3

原式
=5x(y-x)× xy/(x-y)^2*(x+y)(x-y)/x^2
=-5y(x+y)
=-5*(-2/3)(1/2-2/3)
=-5/9