- #1

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A periodic function

*f*has a period of 12. If f(7)=-2 and f(11)=9, determine the value of f (43)

how do you do this?

- Thread starter Aya
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- #1

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A periodic function

how do you do this?

- #2

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Well, 43 - 7 = 36.

- #3

dav2008

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Can you figure out the problem using that fact?

- #4

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or would it be like this

f(x)=f(x+na)

f (43)=f(7+12(-2))

f(43)=-17

- #5

dav2008

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So f(43)=f(43+12)=f(43-12)=f(43+24)...

In your example you say that f(43)=f(7+12(-2)). This is true but it means that f(43)=f(-17).

You are given f(7) and f(11). Can you relate one of those to f(43) somehow?

- #6

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f(7)=(7+12+12+12)

=f(43)

so f(43)=-2

is that right, what about f(11)? or do i not need to use that?

- #7

dav2008

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Yes that's right.

You found out f(43) so I don't know why you're worried about f(11).

You found out f(43) so I don't know why you're worried about f(11).

- #8

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^ ok, thanks

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