Answer
If $ k \gt 0$, the model is a growth model, and
if $ k \lt 0$, the model is a decay model
Work Step by Step
Exponential growth model $: \quad A= A_{0}e^{kt}$.
If $ k \gt 0$, the function models the amount of a growing entity.
$ A_{0}$ is the original amount, or size, of the growing entity at time t = 0,
$ A $ is the amount at time $ t $, and
$ k $ is a constant representing the growth rate.
If k is negative, the model is an exponential decay model
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Given an exponential model, $\quad A= A_{0}e^{kt}$,
if $ k \gt 0$, the model is a growth model, and
if $ k \lt 0$, the model is a decay model
