There is a difference between the two. The exponential function is f (x) = a x (a > 0 and a is not equal to 1) Note: the independent variable of the exponential function must be x, and the coefficient must be 1. For example, F (X) = A (X+ 1) F (X) = 2A X is not an exponential function. These functions are called exponential functions, that is, they are like exponential functions but not exponential functions, and can be compared with the inverse proportional function model.