先化简,再求值.(x+2) 2 -(x+1)(x-1)+(2x-1)(x-2),其中x=-3

2025-01-07 17:18:17
推荐回答(1个)
回答1:

(x+2) 2 -(x+1)(x-1)+(2x-1)(x-2)
=x 2 +4x+4-x 2 +1+2x 2 -4x-x+2
=2x 2 -x+7            
当x=-3时,
原式=2×(-3) 2 -(-3)+7=28.