(x-1/x平方-6x+9)-(1/x-3)-(2x/9-x平方)
问题描述：
(x-1/x平方-6x+9)-(1/x-3)-(2x/9-x平方)
答
原式=（x-1)/(x-3)²-1/(x-3)+2x/(x+3)(x-3)=(x²+2x-3)/(x-3)²(x+3)-(x²-9)/(x-3)²(x+3)+(2x²-6x)/(x-3)²(x+3)=(2x²-4x+6)/(x-3)²（x+3)