Answer
The function is neither linear nor exponential.
Work Step by Step
We can see that the ratio of consecutive vales is not fixed or constant.
That is, $\dfrac{12}{6}=2 \ne \dfrac{18}{12}=1.5$
Thus, the function is not an exponential function.
The difference of consecutive vales is not fixed or constant.
That is, $6-3=2 \ne 12-6=6$
Thus, this does not represent a linear function.
So, we conclude that the function is neither linear nor exponential.
