Answer
$(x+1)(x-16)$
Work Step by Step
The given expression, $
r^2-15r-16
,$ has $c=
-16
$ and $b=
-15
.$
The possible factors of $c$ are $
\{ 1,-16 \}
,\{ 2,-8 \}
\{ 4,-4 \}
\{ -1,16 \}
,\{ -2,8 \}
$. Among these factors, the pair whose sum is equal to $b$ is $\{
1,-16
\}.$ Hence, the factored form is
\begin{array}{l}\require{cancel}
(x+1)(x-16)
.\end{array}