#### Answer

In the exponential function $e^{x}$, $x$ is known as the power (or index), which is the number of times that base $e$ is multiplied by itself. For example, when $x=3$, $e$ is multiplied by itself 3 times (${e}\times{e}\times{e}$). This is what is done when base value $e$ is a positive integer. When $e$ is a negative integer, it is the opposite (or inverse) of a positive value $x$. Thus, instead of multiplying, you would divide. An easy way to solve this is by putting $e^{-x}$ in the form of it's reciprocal, $\frac{1}{e^{x}}$. Solve $e^{x}$ first, and then make it the denominator of $\frac{1}{y}$.

#### Work Step by Step

This vocabulary problem comes directly from the chapter in a call out section titled Exponential Notation.