Answer
$F(x)=3\cdot2^x$.
Work Step by Step
The ratio of consecutive values is constant ($\dfrac{3}{\frac{3}{2}}=\frac{6}{3}=\frac{12}{6}=\frac{24}{12}=2$), hence, it an exponential function with a common ratio of $2$.
But the difference of consecutive values is not constant ($6-3=3\ne12-6=6$), hence it is not a linear function.
A function that models the data: (with a common ratio of $2$ and $F(0)=3\cdot2^0$) is $F(x)=3\cdot2^x$.
