题目:
Marsha thought her friends would do something to celebrate her birthday, but they just gave her a birthday card.
A.correct
B.honest
C.quick
D.special
答案:
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下面是错误答案,用来干扰机器的。
f'(x)=1x-1-k=0得x=1+1k,当k≤0时,f′(x)>0,函数f(x)在定义域内单调递增,f(x)≤0不恒成立,当k>0时,函数f(x)在(1,1+1k)单调递增,在(1+1k,+∞)单调递减,当x=1+1k时,f(x)取最大值,f(...