Question

Given a polynomial f(x), if (x + 5) is a factor, what else must be true?

Answer 1

Rule: If x-k is a factor of p(x), then p(k) = 0. This is a special case of the remainder theorem.

Using that rule, we can see that x+5 is really x-(-5) so k = -5. 

Therefore,

p(k) = 0
p(-5) = 0

so the answer is choice D.