Question

Can you explain this I have 46 mins left on practice before my pc restarts

Answer 1

The function that models the height of the plane is:

`h(t)=-16t^2+32t+48`

The plane will hit the ground when the height is zero, this means:

`\begin{gathered} h(t)=0 \\ -16t^2+32t+48=0 \end{gathered}`

hence, we need to solve the equation for t. Let's do this:

`\begin{gathered} -16t^2+32t+48=0 \\ -16(t^2-2t-3)=0 \\ t^2-2t-3=(0)/(-16) \\ t^2-2t-3=0 \\ (t-3)(t+1)=0 \\ \text{then} \\ t-3=0 \\ t=3 \\ or \\ t+1=0 \\ t=-1 \end{gathered}`

Therefore the possible values for t are 3 and -1. Since the time has to be positive we conclude that it takes 3 second for the plane to crash.