Question 1132994
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If a function is periodic with period 6, then if it is given that f(3) = -1, then the function value is also -1 for any input value that is any multiple of 3 less than or greater than 3.  That is,<br>
..., f(-15) = -1, f(-9) = -1, f(-3) = -1, f(9) = -1, f(15) = -1, ...<br>
So there is the answer to one of your questions.<br>
In a similar manner, what do you know about the values of f(8) and f(20)?<br>
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Added in response to reader's question...<br>
Yes. 20 = 8+2(6), so f(20) = f(8) = 5