对于函数f（x），若f（x）=x，则称x为f（x）的“不动点”；若f[f_爱下问搜题

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问题解答题

对于函数f（x），若f（x）=x，则称x为f（x）的“不动点”；若f[f（x）]=x，则称x为f（x）的“周期点”，函数f（x）的“不动点”和“周期点”的集合分别记为A和B即A={x|f（x）=x}，B={x|f[f（x）=x]}．

（1）求证：A?B

（2）若f（x）=ax²-1（a∈R，x∈R），且A=B≠?，求实数a的取值范围．

答案

略

完形填空

I've spent most of my career as a traveling salesman, and so I know that   36 is an occupational disease．But one year, my   37  gave me the cure for my homesickness．
It had black bright eyes, a red bow tie and orange feet—a stuffed penguin（企鹅）that   38  about five inches tall．Attached to its left wing   39  a little sign with the hand-painted declaration "I Love My Dad! "．I   40  the penguin at once on my table．
On my next trip, I put the penguin in my suitcase．That night when I   41__   home, my daughter Jeanine was   42  because the penguin had disappeared．"Honey, he's here with me, " I explained, "I brought him   43  ."
44 , the penguin came with me—as necessary as my briefcase．And we   __45  along the way．In Albuquerque, I checked into a   46 , dropped my bag and ran to a meeting．When I returned, the maid had   47  the bed and stood the penguin on the pillow．
One night, I discovered the penguin   48 , and after a mad phone call, I learned I' d   49  it in my previous hotel room,   50  it had been rescued by a maid．I __51  a hundred miles to get it, and when I arrived at midnight, the penguin was waiting at the front desk．In the hotel lobby（大厅）, other tired business travelers were   __52   at the reunion of my penguin and me---I think with a bit of   53  ．
Jeanine is in college now, and I don't travel   54  . The penguin sits on my table, a reminder that love is a wonderful traveling companion．All those years on   55 , it was the one thing I never left home without．

A．From now on

B．In the future

D．From then on

A．had friends

C．made friends

D．made friend

D．supermarket

B．the meeting

判断题

随着锅炉内部压力的升高，汽包壁将受到越来越大的机械应力。