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Deriving the formula from a graph

  1. Nov 12, 2013 #1

    adjacent

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    So,here we have a graph.For every unit of 1(x axis),the unit of the previous y axis is multiplied.
    Like this.
    (0,2),(1,4),(2,8),(3,16)........
    I don't know how the formula will be,and had never seen this kind of graph.
    The y seems to be a geometric sequence,on which we can use, ## ar(n-1) ## .r is 2.a is 2
    So 2 x 2(n-1)
    n is the value of x.For every value of x,we can now find the value of y.
    So how can we find the general formula of the graph?Is it ## y=2 x 2(x-1) ## ? I don't think so,If the x values started with 1,it's possible.

    I don't know why LaTeX is not working,Help please.
     
    Last edited: Nov 12, 2013
  2. jcsd
  3. Nov 12, 2013 #2

    LCKurtz

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    Your pairs are ##(n, 2^{n+1})## for ##n=0,1,2,...##.
     
  4. Nov 12, 2013 #3

    adjacent

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    How did you derive that?What could be the general formula? ##y=2^{x+1}## ?
     
  5. Nov 12, 2013 #4

    LCKurtz

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    Yes. You already noticed the ##y## values were powers of ##2##. So it was just a matter of adjusting the exponent to make the ##y## value agree with the ##x## value.
     
  6. Nov 12, 2013 #5

    adjacent

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    Thanks, (lol I take reliable and cheap)
     
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