Answer:
y = 18·8^x
Explanation:
We assume you want a model that looks like y = ab^x.
To find the values of "a" and "b", you can fill in the given numbers and solve the system of equations:
18 = a·b^0
9216 = a·b^3
The first equation tells you ...
18 = a
Dividing the second equation by the first gives ...
9216/18 = (a·b^3)/(a·b^0) = b^3
512^(1/3) = b = 8
The exponential function is ...
y = 18·8^x