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设函数f(x)定义在[-α,α]上,证明: (1)F(x)=f(x)+f(-x),x∈[-α,α]为偶函数; (2)G(x)=f(x)-f(-x),x∈[-α,α]为奇函数; (3)f可表示为某个奇函数与某个偶函数之和。

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听力原文: I just wanted to say well done for getting that contract. You did a great job and we know it wasn’t easy. What would you say to a celebratory meal? I know a very good restaurant near here. I’m sure we could get a table for lunch if you’re free.
—You will hear five recordings.
—For each recording, decide what the main reason is for the phone call.
—Write one letter (A—H) next to the number of the recording.
—Do not use any letter more than once.
—After you have listened once, replay each recording.
A booking a table
B cancelling a meeting
C placing an order
D selling something
E offering a lift
F congratulating someone
G checking an address
H making an appointment

设α1=(1,1,1),α2=(1,2,3),α3=(1,3,t). (1)问当t为何值时,向量组α1,α2,α3线性无关? (2)问当t为何值时,向量组α1,α2,α3线性相关? (3)当α1,α2,α3线性相关时,将α3表示为α1和α2的线性组合.

min x12+2x22-x1x2+4x2+4 s.t. x1+x2+x3=5, x1,x2,x3≥0, 取初始点x(1)=(1,1,3)T.

①the Grammar-Translation Method
②the Natural Approach
③the Communicative Approach
④the Cognitive Approach
⑤the Audiolingual Method
B: theoretical basis
a. the monitor theory
b. structural linguistics
c. the discourse theory
d. traditional linguistics
e. the cognitive theory

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