An object is fired vertically upward with an initial speed of 68.6 meters/second. After t seconds, the height is shown by

y = -4.9 t^2 + 68.6 t meters. Given that this object has an initial speed of 68.6 m/s, what is the maximum height it will reach? How long did it take the rocket to reach the maximum height?

The curve is a parabola which opens downward. As you know, the vertex of

ax^2+bx+c is at x = -b/2a, midway between the roots.