Answer:
(x - 3)(x + 1)(x + 5)
Step-by-step explanation:
I'd use synthetic division instead. If we were to find the roots of the given polynomial, we could from them write the factors as well.
The divisor x + 5 corresponds to root x = -5. Setting up synthetic div.,
-5 ) 1 3 -13 -15
-5 10 +15
-----------------------------
1 -2 -3 0
Since the remainder is 0, we know that -5 is a root and (x + 5) is a factor. Moreover, we know that the coefficients of the quotient are 1, -2 and -3.
1x² - 2x - 3 can be factored: the factors are (x - 3) and (x + 1).
So the end result for this problem is (x - 3)(x + 1)(x + 5).
