Because of the symmetry of the parabola, the vertex is halfway between the two roots. Alternatively, you could put the quadratic into vertex form, which is and read the vertex directly. This will give you the maximum height.
Pedro throws a ball upward at a rate of 20 meters per second from an initial height of 2 meters. The height of the ball above the ground can be approximated by h = -5t^2 + 20t + 2 ...where t represents the amount of time, in seconds, since the ball has been released.
What is the maximum height the ball can be reached?
If you look here, you can see the graph for the function. We are trying to find the maximum point of this graph. We could do this by setting the quadratic equal to 0 and finding the roots, using the quadratic formula or completing the square. Are you aware of either of these methods? Have you come across the vertex form of a quadratic before? If not, then your teacher should really have given you some instruction.