先化简,再求值(x+1)²-(x+2)(x-2),其中-½

问题描述:

先化简,再求值(x+1)²-(x+2)(x-2),其中-½

(x+1)²-(x+2)(x-2)
=x²+2x+1-x²+4
=2x+5
∵-½