SOLUTION
We want to find the value of the function by evaluating it;
[tex]\begin{gathered} w(n)=n^2-1 \\ w(-4) \end{gathered}[/tex]
We do this by inserting -4 into the equation;
[tex]\begin{gathered} w(-4)=(-4)^2-1 \\ =16-1 \\ =15 \end{gathered}[/tex]
Therefore, the answer is 15
