The growth/decay factor of the function f(x) = 2(4)^x represents how much the value of the function grows or decreases for every unit increase in x.
In this case, the function is an exponential function and the growth/decay factor is equal to the base of the exponent, which is 4.
So the growth/decay factor of the function f(x) = 2(4)^x is 4. This means that for every increase of 1 unit in x, the value of the function increases by a factor of 4.