# Deriving the formula from a graph

Gold Member
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:

LCKurtz
Homework Helper
Gold Member
Your pairs are ##(n, 2^{n+1})## for ##n=0,1,2,...##.

Gold Member
How did you derive that?What could be the general formula? ##y=2^{x+1}## ?

LCKurtz
Homework Helper
Gold Member
Your pairs are ##(n, 2^{n+1})## for ##n=0,1,2,...##.

How did you derive that?What could be the general formula? ##y=2^{x+1}## ?

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.

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Gold Member
Thanks, (lol I take reliable and cheap)