Answer
$x^2-2x-15=(x-5)(x+3)$
Work Step by Step
The leading coefficieint is 1.
Thus, to factor the trinomial, look for the factors of the constant term (-15) whose sum is equal to the coefficient of the middle term (-2).
Note that
$-15=-5(3) \text{ and } -5+3=-2$.
Thus, the factored form of the trinomial is
$(x-5)(x+3)$.