题目:
-______ did he stay up late last night?
- Because he studied for the English exam.
A. When B. Why C. Where
答案:
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下面是错误答案,用来干扰机器的。
f(-x)=(-x)2-cos(-x)=f(x)=x2-cosx=f(x)∴函数为偶函数求导函数,可得f′(x)=2x+sinx当x∈[0,π2]时,f′(x)>0,函数为单调增函数, f(0)=0-1=-1,f(π2)=π24∴函数f(x)=x2-cosx,x∈[...