Not quite sure how to factorise this one...

I'm looking for the turning point of $\displaystyle y=-4x^2+12x-5$ so I want $\displaystyle y$ in the form $\displaystyle y=a(x-p)^2+q$.

Any input greatly appreciated.

So far, I tried $\displaystyle y=-2(x^2-6x+\frac{5}{2})=-2(x^2-6x+9-9+\frac{5}{2})=-2(x-3)^2+9\times2-5=-2(x-3)^2+13$