How can you tell whether an exponential model describes exponential growth or exponential decay?

An exponential model is of the form $A=A_0{e}^{kt}$ where $A_0$ is the original amount or size of the entity at t = 0, A is amount or size at time t, and k is a constant representing the rate of growth decay.
If k > 0, then the model represents a growing quantity and k is called as the growth rate.
If k <0, then the model represents a decaying quantity and k is called as the decay rate.
So, we can tell whether an exponential model describes exponential growth or decay using the value of k.
Step 2
Conclusion:
Therefore, we can tell whether an exponential model describes exponential growth or decay using the value of k.