Question

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Answer 1

We know that:

- the height in feet t seconds after launch is given by

`s=-16t^2+v_0t`

And we must find the times that the projectil will reach a height of 80ft and when v0 = 96 feet per second

To find it we need to replace s = 80 and v0 = 96 in the formula

`80=-16t^2+96t`

Then, we must solve the equation for t

1. we must move all terms aside

`80+16t^2-96t=0`

2. we must extract the common factor 16

`16(5+t^2-6t)=0`

3. we must factor

`16(t-5)(t-1)=0`

4. we must solve for t

We have two possible results

`\begin{gathered} 1. \\ 16(t-5)(t-1)=0 \\ t-5=0 \\ t=5 \\ 2. \\ 16(t-5)(t-1)=0 \\ t-1=0 \\ t=1 \end{gathered}`

ANSWER:

A. 1, 5 seconds