Question

How do you use the remainder theorem to find which if the following is not a factor of the polynomial `x^3-5x^2-9x+45 div x+5`?

Answer 1

The remainder is `=-160`, so `(x+5)` is not a factor

Explanation:

Let `f(x)=x^3-5x^2-9x+45`
then `f(-5)=-125-125+45+45=-160`
The remaider is `=-160`
`:.` `(x+5)` is not a factor of `x^3-5x^2-9x+45`