先化简,再求值:4(x-2)(x+2)-(4x+1)(x-2),其中x=-9/7
问题描述:
先化简,再求值:4(x-2)(x+2)-(4x+1)(x-2),其中x=-9/7
答
4(x-2)(x+2)-(4x+1)(x-2)
=(x-2)(4x+8-4x-1)
=7(x-2)
=7*(-9/7-2)
=-23