Deducing a coefficient from a cubic polynomial? I fully answered the question, and got that $k=-3$, but the answer says it's positive. Can anyone show me my mistake?
"Given that $x-2$ is a factor of the polynomial $x^3 - kx^2 - 24x + 28$, find $k$ and the roots of this polynomial."
Using factor theorem, I realised that $P(2)$ is equivalent to $0$, therefore $2^3 - 2^2k - 24(2) + 28 = 0$
I solved it algebraically and got that $k=-3$, but the answers say it was $k=3$. Did I make a simple error?
Any help would be appreciated. 

I got k = -3 also. I think the answers may be wrong:
2 | 1     -k      -24           28
  |        2      2(-k + 2)     4(-k + 2)-48
  |____________________________________________
    1   (-k + 2)  2(-k + 2)-24  4(-k + 2)-48+28

-4k+8-48+28 = 0
-4k = 12
k = -3 

