We want our exponential function to look like
y = ab^x.
Let a = the initial y-value.
Our initial value is the first number given for f(x). So, a = 3.
Let b = the number that is needed to go from 3 to 6 to 12 to 24 to 48.
We find b by division.
So, b = the next number divided by the previous.
So, b = 6/3 = 2.
We now plug in our values into the general formula above.
y = ab^x
Answer: y = (3)(2)^x