The general formula for exponential growth and decays is:
if k>0 then then it is an exponential growth function. If k<0 then the function represents an exponential decay.
Now we need to classify each of the functions:
1.
The function
can be wrtten as:
comparing with the general formula we notice that k=2, therefore this is an exponential growth.
2.
The function
can be written as:
comparing with the general formula we notice that k=-4, therefore this is an exponential decay.
3.
The function
comparing with the general formula we notice that k=-1, therefore this is an exponential decay.
