【简答题】已知函数f(x)=x 3 +ax 2 +bx+c(a,b,c∈R),当且仅当x=1,x=-1时,f(x)取得极值,并且极大值比极小值大c. (1)求常数a,b,c的值; (2)求f(x)的极值.
【判断题】函数 的f(x)极大值不一定比极小值大 。
【判断题】若函数y=f(x)存在极大值和极小值,则极大值一定比极小值大
【单选题】在数据库设计中,用 ER 图来描述信息结构,但不涉及信息在计算机中的表示,它属于数据库设计的 () 阶段 。
【单选题】听力原文:M: Since you have visited so many countries, you must be able to speak several different languages. W: I wish I could. But French and German are the only foreign languages I have ever learned to ...
A.
She hasn't learned French.
B.
She can speak several foreign languages including French.
C.
She can speak both German and French.
D.
She speaks neither French nor German.
【单选题】习近平总书记指出,我们要构建以()为核心的新型国际关系,打造人类命运共同体。