Answer
$\text{exponential decay;}\\
\text{exponential growth}$
Work Step by Step
The two types of exponential functions are (1) exponential decay, and (2) exponential growth.
An exponential decay is a type of exponential function where the value of $y$ decreases as the value of $x$ increases.
An exponential growth is a type of exponential function where the value of $y$ increases as the value of $x$ increases.
Thus, the missing expressions in the given statements, in order are:
$\text{exponential decay;}\\
\text{exponential growth}$
