# help with this polynomial

• August 5th 2012, 07:25 AM
anthonye
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.
• August 5th 2012, 07:37 AM
skeeter
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 $f(2) = 0$ ?
• August 5th 2012, 10:59 AM
anthonye
Re: help with this polynomial
Got it thanks Skeeter its the top one.