(2x-6)/(x-2)÷[(5-x)/(x-2)-2]=(2x-6)/(x-2)÷{[(5-x)-2(x-2)]/(x-2)}=(2x-6)/(x-2)÷[(9-3x)/(x-2)]=2(x-3)/(x-2)×(x-2)/[-3(x-3)]=-2/3
等于 负2
=(2x-6)/(5-x-2)=(2x-6)/(3-x)=-2
20
-2
