The height of a projectile launched upward at a speed of 32 feet/second from a height of 48 feet is given by the function: h(t)=-16t^2+32t+48. How long will it take the projectile to hit the ground?

Question

Please help. Thank you

Answer 1

h(t)=0 when the projectile falls to the ground so -16t²+32t+48=0.

If we divide through by -16 we get t²-2t-3=0=(t-3)(t+1) when factorised.

So either t-3=0 or t+1=0. The only positive solution is t=3 seconds, so it takes 3 seconds to fall to the ground.