已知定义域为D的函数f（x），对任意x∈D，存在正数K，都有|f（x_爱下问搜题

搜题请搜索小程序“爱下问搜题”

问题填空题

已知定义域为D的函数f（x），对任意x∈D，存在正数K，都有|f（x）|≤K成立，则称函数f（x）是D上的“有界函数”．已知下列函数：①f（x）=2sin x；②f（x）=

1-x2

；③f（x）=1-2^x；④f（x）=

x

x2+1

，其中是“有界函数”的是 ______．（写出所有满足要求的函数的序号）

答案

①中|f（x）|=|2sinx|≤2 为有界函数

②中|f（x）|≤1 为有界函数

③f（x）＜1 不是有界函数

④|f(x)|=

|x|

x2+1

=

1

|x|+

1

|x|

≤

1

2

(x≠0)

当x=0时，f（x）=0

总之|f(x)|≤

1

2

是有界函数

故答案为：①②④

完形填空

When Julie was a child, she was a very big fan of animals. As a result, 36 she ever heard growing up was “Julie, you should be a vet. You’re going to be a great vet. That’s what you should do.” 37 when she got to the Ohio State University, she started studying to be a vet.
A scholarship allowed her to spend her 38 year studying abroad in Manchester, England. Away from the family 39 back home, she found herself one day sitting at her desk, surrounded by biology books and staring out the window, when it suddenly hit her: “I’m in total 40 . I don’t want to be a vet!”
41 she thought back over all the things she’d done in her life and what had made her happy. And then it hit her—it was all of the youth leadership conferences that she had volunteered 42 , and the communications and leadership courses she had taken as elective courses back at Ohio State. “How could I have been so 43 ? Here I am in my fourth year at school and just finally realizing I’m on the 44 path. I just never took the time to 45 it until now, ” she thought.
Inspired by her new 46 , Julie spent the rest of her year in England taking courses in communications and media studies. When 47 to Ohio State, she was eventually able to 48 the administration to let her create her own program in “leadership studies”, 49 it took her 2 years longer to finally graduate. She 50 to become a senior management consultant in leadership training and development for the Pentagon. She 51 founded a drug-prevention organization that 52 the message “Lead your own life with the skill and the 53 to say no.”
So, never live someone else’s 54 . If you limit your 55 only to what seems possible or reasonable, you disconnect yourself from what you truly want.

C．intellectual

D．intelligent

A．acknowledge

B．information

C．understanding

单项选择题

为使用方便和减少积累误差，选用量块是应尽量选用（）的块数。

A、很多

B、较多

C、较少

D、5块以上