# Thread: Find zeros of cubic polynomial without a constant term

1. ## Find zeros of cubic polynomial without a constant term

Hi,

Could someone assist with this problem.

F(x)=5x-x^3

Here is what I did:

-x(x^2+5)

I tried synthetic division using +-1, +-5, with no luck.

Thanks.

RB

2. ## Re: Find zeros of cubic polynomial without a constant term

$5x-x^3 = x(5 -x^2) = x(\sqrt{5}-x)(\sqrt{5}+x)=0 \implies x=0, \, x= \pm \sqrt{5}$

3. ## Re: Find zeros of cubic polynomial without a constant term

Thank you very much, Skeeter!