You can
put this solution on YOUR website!There are several ways to approach this. If you are familiar with derivatives. take the first derivative and solve for 0.
If you prefer to plot and see
If you want to use just an algebraic approach, note that the equation is in the form of a parabola. Then either use the formauls for the vertex or find the zeros and then follow the verticla line that is halfway between those two points. For this equatuon, the zeros can be found by solving for

So there are zeros at x = 0 and x=12. The point halfway between them is x=6. So the vertex is on the vertical line x=6. Solving yields
All of the methods will get you to the answer x=6