题目

设的导数为,若函数的图象关于直线对称,且.（1）实数的值；（2）求函数的极值. 答案：【答案】（1）；（2）的极大值是,极小值是.【解析】试题分析：（1）先对求导，的导数为二次函数，由对称性可求得，再由即可求出；（2）对求导，分别令大于和小于，即可解出的单调区间，继而确定函数的极值.试题解析：（1）因,故,从而,即关于直线对称,从而由条件可知,解得,又由于,即解得.（2）__________ of all was that not a sound could be heard. A．It frightened us most B．The thing that most frightened us C．We were most frightened by D．What frightened us most