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## Main Question or Discussion Point

write a function that starts at 20 and triples every 7

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write a function that starts at 20 and triples every 7

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arildno

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Utilize that knowledge to find a solution to your problem.

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You could use the exponential function in a general form and start fitting it to the two conditions you have, however there is a slightly more advanced way. Write out the two conditions as:

[tex]f(0)=20[/tex]

[tex]f(7x)=2f(x)[/tex]

Take the derivative of the second one and use in it the original again. You will end up with a first order differential equation giving as solution the exponential function. Using the first equation as boundary gives then the function you are looking for.

Can you do this?

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