Question

Which of these are factors of this polynomial?

-3x3 + 15x2 + 3x - 15
0 (x + 1)
3x
(3x - 1)
(x - 5)
-3
(x + 5)
(x - 1)
0
0

Answer 1

Answer: -3(x^2 + 1)(x-5)

Explanation: -3x^3 + 15x+3x -15
Factor by grouping: -3x^2(x-5) +3(x-5)
Combine: (-3x^2 +3)(x-5)
Factor by GCF: -3(x^2 +1)(x-5)
Set equal to zero: (x^2 +1)=0
(x+5)=0
Solve: x=5, x=square root of 1