Question

Can we conclude that x - 5 is a factor of the polynomialHow do you know?

Answer 1

Recall that:

x-a is a factor of a polynomial p(x) if and only if p(a)=0.

Evaluating the given polynomial at x=5 we get:

`5^3-5^2-17\cdot5-15=125-25-85-15=0.`

Therefore x-5 is a factor of the polynomial x³-x²-17x-15.