Since function g is defined as g(x) = kf(x), the value of k is equal to 2.
In Mathematics and Geometry, a function can be stretched by multiplying it with a numerical value that is either greater than 1 or less than -1.
By critically observing the graph of these exponential functions, we can reasonably infer and logically deduce that the graph of f(x) pass through the point (8, 3) and the graph of f(x) pass through the point (8, 6).
In this context, we can set up an equation that model the graph as follows;
g(x) = kf(x)
g(8) = kf(8)
6 = k3
k = 6/3
k = 2.
In conclusion, the parent exponetial function, f(x), was vertically stretched by a factor of 2, in order to produce the graph of the transformed exponetial function, g(x).