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# Analyzing graphs of exponential functions

Given the graph of an exponential function, Sal finds the formula of the function and a value that is outside the graph.

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• btw :)
1/81 = 0.012345679012345678
• Actually, 1/81 is a repeating decimal with a 9 digit repeat pattern. 1/81 = 0.012345679012345679012345679... with the digits 012345679 repeating.
• What if I only know 2 distant points, let's say (6,28) and (30,8) , how do I find the equation ?
• Megan's comment is correct if you don't know what type of function it is. If you knew it was an exponential function of the form a*(r)^x, the you could construct a system of equations to get you the equation. For example, the exponential equation that roughly goes through the points (6, 28) and (30, 8) is:

y = 38.1*(0.95)^x

You can graph the function on desmos to see for yourself. Hope this helps!