An exponential function

Question

An exponential function  passes through the points (0, 9000) and (3, 9). What are the values of and ?

I got the value of a which was 9000 but I don't understand how to get B I thought it was 3 but it said it was wrong.

Answer 1

f(x) = ab^x

Since (0, 9000) is on the graph, 9000 = ab⁰. So, a = 9000.

f(x) = 9000b^x

Since (3,9) is on the graph, 9 = 9000b³

So, b³ = 1/1000

b = 1/10 = 0.1

Therefore, f(x) = 9000(0.1)^x

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