definition: generally, a function of the form y=a^x (a>0 and a≠1) (x∈r) is called an exponential function. that is to say, a function with an index as an independent variable, a power as a dependent variable, and a constant base is an exponential function. it is one of the elementary functions. can be extended to be defined as an analytic function on c.

general formula y=a^x(a>0 and a≠1) (x∈r)