阅读下面材料,再解方程:解方程x2−|x| −2=0解:当x≥0时,原方程化为x2−x−2=0,解得:x1=2,x2= −1(不合题意,舍去)当x<0时,原方程化为x2 + x −2=0,解得:x1=1,(不合题意,舍去)x2=−2∴原方程的根是x1="2," x2= −2 请参照例题解方程x2−|x−1|−1=0
先化简,再求值:,其中.
计算: (x+1)2-2(x-2).
计算:.
计算: