Answer
$(x+3)(x-5)$
Work Step by Step
The given expression, $
x^2-2x-15
,$ has $c=
-15
$ and $b=
-2
.$
The possible factors of $c$ are $
\{ 1,-15 \}
,\{ 3,-5 \}
,\{ -1,15 \}
,\{ -3,5 \}
$. Among these factors, the pair whose sum is equal to $b$ is $\{
3,-5
\}.$ Hence, the factored form is
\begin{array}{l}\require{cancel}
(x+3)(x-5)
.\end{array}
