Answer:
A general exponential equation is written as:
f(x) = A*(r)^x
Where:
A is the initial value, this is the value that the function takes when x = 0.
r is the rate of growth
x is the variable.
In this case, the function is:
f(x) = 2*(4)^x
The initial value is:
f(0) = 2*(4)^0 = 2*1 = 2
The initial value is 2.
And the rate of growth is 4.
So Martin seems to mixed these two values (he said initial value = 4, and rate = 2, which is the opposite of what we found)