Just answer the question if you actually answer it you get brainliest and 50 points.
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Step-by-step explanation:
f(x) = a * b^x
We have the following information:
f(0) = a * b^(0) = 15. => a * 1 = 15, a = 15.
f(1) = a * b^(1) = 9. => a * b = 9, (15) * b = 9, b = 0.6.
Hence f(x) = 15 * 0.6^x.