(2x-6)除以(X平方-4x+4)除以(x+3)乘以(x平方+x-6)除以(12-4x)=2(x-3)/(x-2)^2/(x+3)*(x+3)(x-2)/4(3-x)=-2(x-3)/[(x-2)^2*(x+3)]*(x+3)(x-2)/4(x-3)=-1/2(x-2)
原式=[2(x-3)/(x-2)²]÷(x+3)×(x+3)(x-2)/[-(x-3)]=-2(x-3)(x+3)(x-2)/[(x-2)²(x+3)(x-3)]=-2/(x-2)