原式=[(x+3)/(x+3)(x-3)-x/(x-3)(x+2)][(3-x)/(4x-6)]=[1/(x-3)-x/(x-3)(x+2)][(3-x)/(4x-6)]={[(x+2)-x]/(x-3)(x+2)}[-(x-3)/(4x-6)]=-[2/(x-3)(x+2)][(x-3)/2(2x-3)]=-1/(x+2)(2x-3)=-1/(2x²+x-6)