Exponential function: generally speaking, the function y = ax (a > 0, and a≠ 1) is called exponential function, where x is the independent variable. The domain of a function is r.
Logarithmic function is the inverse function of exponential function, and the textbook is based on the property that the images of two functions as inverse functions are symmetrical about the straight line y = X.
The function y = x a is called a power function, where x is an independent variable and a is a constant (only the case where a is a rational number n is discussed here).