2x-6/x的平方-4x+4除以12-4x/x的平方+x-6乘以1/x+3

(2x-6)/(x²-4x+4)÷(12-4x)/(x²+x-6)*1/(x+3)
=(2x-6)/(x²-4x+4)*(x²+x-6)/(12-4x)*1/(x+3)
=2(x-3)/(x-2)²*(x+3)(x-2)/[4(3-x)]*1/(x+3)
=2(x-3)/(x-2)*1/[2(3-x)]
=-(x-3)/(x-2)*1/[2(x-3)]
=-1/[2(x-2)]
=-1/(2x-4)