原式=(x-1)/(x+1)(x+2)-6/(x-2)(x+1)-(x-10)/(x+2)(x-2)
=[(x-1)(x-2)-6(x+2)-(x-10)(x+1)]/(x+1)(x+2)(x-2)
=(x²-3x+2-6x-12-x²+9x+10)/(x+1)(x+2)(x-2)
=0/(x+1)(x+2)(x-2)
=0