help with this polynomial

**anthonye** · August 5th 2012, 06:25 AM

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.

**skeeter** · August 5th 2012, 06:37 AM

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 $f(2) = 0$ ?

**anthonye** · August 5th 2012, 09:59 AM

Got it thanks Skeeter its the top one.

Thread: help with this polynomial