The function in your post is written/presented INCORRECTLY.
The correct writing is f(x) = a*c^x, or f(x) = .
The given sequence in "y" is the geometric progression with the first term of 2 and the common ratio of 3.
So, f(x) = 2*3^x, where x = 0, 1, 2, 3, 4.
Thus a = 2; c = 3. ANSWER