先化简,再求值.(x+1)(4x-1)-(2x-1)2,其中 x=-2.

问题描述:

先化简,再求值.(x+1)(4x-1)-(2x-1)2,其中 x=-2.

(x+1)(4x-1)-(2x-1)2
=4x2-x+4x-1-(4x2-4x+1)
=4x2-x+4x-1-4x2+4x-1
=7x-2,
当x=-2时,原式=7×(-2)-2=-14-2=-16.