The equation of an exponential function can be written in the form $f(x) = ab^x$, where $a\neq 0$, $b>0$, and $b\neq1$. The graph of an exponential function is either strictly increasing or strictly decreasing. The graph has a horizontal asymptote, which is a horizontal line that the curve approaches as $x$ approaches infinity or negative infinity. All exponential functions can be graphed as transformations of the parent function $f(x) = b^x$. A data set displayed in a scatterplot may approximate the shape of the graph of an exponential function. Technology can be used to generate an exponential function that best fits the data.
At A Glance
 The rule for an exponential function includes a variable as an exponent.
 The base of an exponential parent function determines whether the function is increasing or decreasing.

Transformations can be used to graph exponential functions.

Exponential growth and decay can be modeled using exponential functions. Exponential growth has an increasing exponential function, while exponential decay has a decreasing exponential function.
 Technology can be used to generate an exponential function that best fits the exponential relationship between two variables.