Question

In total, how long is the golf ball in the air?

Answer 1

4.46

1) Note that this quadratic model describes a parabola that opens down.

We need to find the zeroes of this quadratic equation.

2) So, we can write down the following:

`\begin{gathered} -13x^2+65x=0 \\ \\ -13x^2+65-65=0-65 \\ \\ -13x^2=-65 \\ \\ (-13x^2)/(-13)=(-65)/(-13) \\ \\ x^2=5 \\ \\ x=\pm√(5) \end{gathered}`

Note that the square root of five is approximately 2.23. We can pick the second root and subtract from that the first root

`\begin{gathered} t=|-2.23-2.23| \\ t=|4.46| \\ t=4.46 \end{gathered}`

3) Thus, we can tell that the ball has been flying for approximately 4.46 seconds.