先化简再求值:(x+2-12/x-2)/(4-x)/(x-2),其中x=-1/2

分类: 作业答案 • 2021-12-31 13:51:24

问题描述：

答

(x+2-12/x-2)/(4-x)/(x-2),其中x=-1/2
=(x²-4-12)(x-2)÷(4-x)/(x-2)
=(x²-16)/(4-x)
=-(4-x)(4+x)/(4-x)
=-4-x
=-4+1/2
=-3.5