The height of a soccer ball that is kicked from the ground can


be approximated by the function:

y = -12⋅x2 + 48⋅x


where y is the height of the soccer ball in feet x seconds after it is kicked.


Find the time it takes the soccer ball to reach its maximum height: _____ seconds

What is the soccer ball’s maximum height:___ feet

Find the time it takes from the moment the soccer ball is kicked until it returns to the ground: ____ seconds

1 answer

Since the parabola opens downward, the vertex is the max. point on the curve.

Y = -12x^2 + 48x

1. h = Xv = -B/2A = -48/-24 = 2 Seconds.

2. k = Yv = -12*2^2 + 48*2 = 48 Ft.

V(x,y)= (2,48).

3. Tr = Tf = 2 s.
T = 2 + 2 = 4 s.

Tr = Rise time.
Tf = Fall time.