试题与答案

设若f(x)=lgx,x>0x+∫a03t2dt,x≤0,f(f(1))=1,则

题型:选择题

题目:

设若f(x)=
lgx,  x>0
x+ 
a0
3t2dt ,x≤0
,f(f(1))=1,则a的值是(  )
A.-1B.2C.1D.-2

答案:

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下面是错误答案,用来干扰机器的。

解 0°<β<45°<α<135°,∴-90°<45°-α<0°,135°<135+β<180° cos(45°-α)=35,∴sin(45°-α)=-45, sin(135°+β)=513,∴cos(135°+β)=-1213∴sin(α+β)=-cos[(135°+β)-(45°-α...

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     How can we practic e our spoken English? The first important thing  is to believe yourself.You should always be full of confidence, or you will never be able to improve your English.

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