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Math Help - Functions graph problem

  1. #1
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    May 2011
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    Functions graph problem

    So first here is the graph: http://i56.tinypic.com/b8muja.png

    The question is:
    The figure above shows a portion of a graph of the function f. If f(x+5)=f(x) for all values of x, then f(x)=0 for how many different values of x between 0 and 12?

    the book says the answer is 9, but i do not know how i would get that answer?
    So how would i get that answer? thanks
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  2. #2
    Junior Member
    Joined
    Aug 2009
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    Brisbane, Australia
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    For starters, you have labeled the vertical axis "y". Does the book label the vertical axis as y? The vertical label should be f(x), because nowhere in this problem is a variable y referenced. I will assume you have labeled it as y out of habit...

    So, f(x) = 0 when y = 0. How many times between 0 and 5 do you see the graph cross the x axis? Where it crosses is where f(x) = y = 0. We know that the graph repeats its pattern every 5 units of x, so how many times do you count it will cross between 0 and 12? The answer in the book is correct.
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  3. #3
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    Thank you borophyll , oh and the book does label the vertical axis as y. Thank you very much!!!
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