（x+2）/（x－1）·（x²－2x+1）/（x²－x－6）－（2x+6）／（x²－9）=(x+2)/(x-1)X(x-1)²/(x+2)(x-3)-2(x+3)/(x+3)(x-3)=(x-1)/(x-3)-2/(x-3)=(x-1-2)/(x-3)=(x-3)/(x-3)=1
