化简：(x^2+3x+9)/(x^3-27)+6/（9-x^2)-(x-1)/(6+2x)
问题描述：
化简：(x^2+3x+9)/(x^3-27)+6/（9-x^2)-(x-1)/(6+2x)
答
原式=(x²+3x+9)/(x-3)(x²+3x+9)-6/(x+3)(x-3)-(x-1)/2(x+3)=1/(x-3)-6/(x+3)(x-3)-(x-1)/2(x+3)=(2x+6-12-x²+4x-3)/[2(x+3)(x-3)]=-(x²-6x+9)/[2(x+3)(x-3)]=-(x-3)²/[2(x+3)(x-3)]=(3-x)/...