When finding the zeros of the vertex do you substitue zero for y or x or both in the quadratic equation? Will it work if the graph doesnt touch the zero on either axis?
The zeros are the points where the graph meets the x axis, and they correspond to y = 0.
If the graph doesn't touch the x axis then there are no real zeros. This is the case if the quadratic formula ends up with a negative under the square root sign. Since the square root of a negative number is not a real number, the quadratic formula would in this case tell you that there are no real zeros.