If -1 and 4 are both roots of a given polynomial, then which of the following must be a factor of the polynomial?
(A) x – 1
(B) x2 + 3x − 4
(B) x2 – 3x − 4
(D) x + 4
Choice C is correct.
Since, -1 and 4 are both roots of a given polynomial.
Therefore, (x+1) and (x-4) must be factors of the given polynomial.
Hence, their product must also be a factor of given polynomial.
The product of the factors = (x+1)(x-4)
= x2 – 3x − 4