Question

A football is punted in the air. The graph of the equation shows it reached its maximum height after being in the air for 2.5 seconds. Which of the following is NOT true?Select the correct response!The y value of the vertex will be the maximum height.The 'a' value of the equation will be negative.The "a" value of the equation will be positiveThe x value of the vertex will be 2.5.

Answer 1

The height over time of a football can be represented by a quadratic equation.

The graph of this type of equation is a parabola.

Since the graph has a maximum value (the maximum height occurs for t = 2.5 seconds), that means the parabola opens downwards and the value of "a" is negative:

$h=at^2+bt+c$

The y-value of the vertex is the maximum height, the value of "a" is negative and the x-value of the vertex is 2.5, therefore the correct response is the third one.