The table below represents a linear function.
\def\arraystretch{1.5} \begin{array}{|c|c|c|c|c|} \hline n & -3 & 1 & 5 & 9 \\ \hline f(n) & -3 & 5 & 13 & 21 \\ \hline \end{array}
n
f(n)
​

−3
−3
​

1
5
​

5
13
​

9
21
​

​

​What is the slope?