Quadratic

Combine like terms to get..

$3x^2+6x-9$

Then isolate the $x^2$ and $x$ terms and we get $3(x^2+2x) - 9$. 

Then complete the square inside the parentheses to get $3(x^2+2x+1) - 9 - 1 \cdot 3$ .

Then factor the parentheses and simplify to get $3(x+1)^2 - 12$.

You should be able to finish from here.