$\displaystyle 3p^2-12p+2=0$

$\displaystyle p^2-4p+\frac{2}{3}=0$

Completing the square

$\displaystyle (\frac{4}{2})^2=4$ and $\displaystyle \frac{2}{3}+x=4$ so add $\displaystyle \frac{10}{3}$ to each side.

$\displaystyle p^2-4p+4=\frac{10}{3}$ which is $\displaystyle (p-2)^2=\frac{10}{3}$

I end up with $\displaystyle p=2 \pm \sqrt{\frac{10}{3}} $

The book says $\displaystyle \frac{6 \pm \sqrt{30}}{3}$

Whats up with that?