y = abx
Point (1, 4): 4 = ab
Point (3, 16): 16 = ab^3
From 4=ab we have a = 4/b
Substitute into 2nd equation
16 = (4/b)b^3
16 = 4b^2
4 = b^2
2 = b
a = 4/b = 4/2 = 2
An exponential function that fits is: y = 2(2^x)
check: x=1; y = 2(21) = 4 ... point (1, 4)
x=3: y = 2(23) = 2(8) = 16 ... point (3, 16)
