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