Question 1153458

The height of a projectile launched upward at a speed of {{{32(ft/s)}}} from a {{{h=48}}} feet is given by the function: 

{{{h(t)=-16t^2+32t+48}}} How long will it take the projectile to hit the ground?

the projectile will hit the ground when {{{h(t)=0}}}

{{{0=-16t^2+32t+48}}} ......factor

{{{0=-16(t^2-2t-3)}}} 

{{{0=-16(t^2-3t+t-3)}}}

 {{{0=-16((t^2-3t)+(t-3))}}}

 {{{0=-16(t(t-3)+(t-3))}}}

{{{0=-16((t+1)(t-3))}}}

we need only positive solution for the time


{{{t=3}}}

Therefore, the time is {{{ 3s}}}