# Math Help - help with this polynomial

1. ## help with this polynomial

Hi;

got this question
Given that
x -2 is a factor of the polynomial x^3 - kx^2 -24x + 28, find k.

I get k=-3 they get k=3.

Pretty sure I'm right just need confirmation.

Thanks.

2. ## Re: help with this polynomial

confirm it yourself ...

$f(x) = x^3 + 3x^2 - 24x + 28$ if $k = -3$

or

$f(x) = x^3 - 3x^2 - 24x + 28$ if $k = 3$

which one yields $f(2) = 0$ ?

3. ## Re: help with this polynomial

Got it thanks Skeeter its the top one.