Tom throws a ball into the air. The ball travels on a parabolic path represented by the equation [tex]h = -8t^2 + 40t[/tex], where [tex]h[/tex] represents the height of the ball above the ground and [tex]t[/tex] represents the time in seconds. The maximum value achieved by the function is represented by the vertex. Use factoring to answer the following:

1. How many seconds does it take the ball to reach its highest point?
2. What ordered pair represents the highest point that the ball reaches as it travels through the air?

Hint: Because parabolas are symmetric, the vertex of a parabola is halfway between the zeroes of the quadratic.



Answer :

To solve this problem, let's go through the steps methodically.

1. Expression for the height of the ball:
The height of the ball as a function of time [tex]\( t \)[/tex] is given by the quadratic equation:
[tex]\[ h = -8t^2 + 40t \][/tex]

2. Find the zeros of the equation:
To find the time at which the ball touches the ground (height [tex]\( h \)[/tex] becomes zero), we need to solve the equation:
[tex]\[ -8t^2 + 40t = 0 \][/tex]

We can factor out [tex]\( -8t \)[/tex] from the equation:
[tex]\[ -8t(t - 5) = 0 \][/tex]

This gives us two solutions:
[tex]\[ t = 0 \quad \text{or} \quad t = 5 \][/tex]

These are the times when the ball is at the ground level.

3. Determine the time at which the ball reaches its highest point:
Since the vertex of a parabola is symmetric and lies exactly halfway between the zeros, we calculate the midpoint between [tex]\( t = 0 \)[/tex] and [tex]\( t = 5 \)[/tex]:
[tex]\[ t_{\text{highest}} = \frac{0 + 5}{2} = 2.5 \][/tex]

So, the ball reaches its highest point at [tex]\( t = 2.5 \)[/tex] seconds.

4. Calculate the highest point (height) of the ball:
We substitute [tex]\( t = 2.5 \)[/tex] back into the original height equation to find the highest height:
[tex]\[ h_{\text{highest}} = -8(2.5)^2 + 40(2.5) \][/tex]

Evaluating this expression:
[tex]\[ h_{\text{highest}} = -8 \times 6.25 + 40 \times 2.5 \][/tex]
[tex]\[ h_{\text{highest}} = -50 + 100 \][/tex]
[tex]\[ h_{\text{highest}} = 50 \][/tex]

So, the maximum height [tex]\( h \)[/tex] that the ball reaches is 50 units.

5. The ordered pair representing the highest point:
The highest point the ball reaches can be represented as the ordered pair [tex]\(( t_{\text{highest}}, h_{\text{highest}} )\)[/tex]:
[tex]\[ \left( 2.5, 50.0 \right) \][/tex]

Summary:

- The ball takes 2.5 seconds to reach its highest point.
- The ordered pair representing the highest point that the ball reaches is [tex]\( \left( 2.5, 50.0 \right) \)[/tex].

These results indicate the vertex of the parabola formed by the ball's trajectory.