(x/x2-9)-(1/x2+6x+9)计算
问题描述：
(x/x2-9)-(1/x2+6x+9)计算
答
(x/x2-9)-(1/x2+6x+9)=x/(x+3)(x-3)-1/(x+3)²
=[x(x+3)-(x-3)]/(x-3)(x+3)²
=[x²+3x-x+3]/(x-3)(x+3)²
=(x²+2x+3)/(x-3)(x+3)²