You can use the quadratic formula to find the zeroes: x=(-12+sqrt(144-4*2*9))/4 (using your values of a, b and c). So x=(-12+sqrt(72))/4. 72=4*9*2 so sqrt(72)=6sqrt(2) and x=(-6+3sqrt(2))/2. From this we can see the vertex because the zeroes are equidistant from the vertex on either side. If we ignore the radical the vertex is at x=-3 (that is, -6/2), and the zeroes are given by the quadratic solution, 3sqrt(2) on either side of the vertex. Sqrt(2)=1.4142 approx. so 3/2 times this is 3*0.7071=2.1213, making the zeroes -0.8787 and -5.1213. When x=-3, y=-9 so the vertex is at (-3,-9). The axis of symmetry is the line x=-3. The graph is a parabola with a U shape where the arms are moving apart. The curve cuts the y axis at y=9 (x=0). The U is symmetrical about the line x=-3.