题目内容
已知函数f(x)=Asin(ωx+ϕ),(A>0,ω>0,0≤ϕ≤π)的部分图象如图所示,记

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【答案】分析:先求出函数f(x)=2sin(
),求出f(1)、f(2)、f(3)、…f(8 )的值,根据函数的周期性求出
的值.
解答:解:由函数f(x)的图象可得,此函数的周期等于8,A=2,∴
=8,ω=
.
把点(0,0)代入函数f(x)的解析式可得∅=0.
故函数f(x)=2sin(
).f(1)=
,f(2)=2,f(3)=
,f(4)=0,
f(5)=-
,f(6)=-2,f(7)=-
,f(8)=0.
故 f(1)+f(2)+f(3)+…+f(8)=0.
∴
=
+f(25)+f(26)+f(27)=0+f(1)+f(2)+f(3)=2+2
.
故答案为:2+2
.
点评:本题主要考查函数f(x)=Asin(ωx+ϕ)的周期性以及根据图象求解析式,求出函数f(x)=2sin(
),是解题的关键.


解答:解:由函数f(x)的图象可得,此函数的周期等于8,A=2,∴


把点(0,0)代入函数f(x)的解析式可得∅=0.
故函数f(x)=2sin(



f(5)=-


故 f(1)+f(2)+f(3)+…+f(8)=0.
∴

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
故答案为:2+2

点评:本题主要考查函数f(x)=Asin(ωx+ϕ)的周期性以及根据图象求解析式,求出函数f(x)=2sin(

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