Question

How do I do number 5?

Answer 1

H(t)=-16t^2+15t+12
(e)
maximum height is reached when h'(t)=-32t+15=0, or tm=15/32 seconds.
maximum height reached = h(tm)=h(15/32)=-16(15/32)^2+15(15/32)+12
=993/64 ft
=15.516 ft.
(f) when Greg reaches water, h(t)=0=-16t^2+15t+12
Solve for t using quadratic formula,
t=[-15+/- sqrt(15^2+4*12*16)]/(2*-16)
=-0.516s or 1.4535s.
Reject negative root so
Greg reaches water at t=1.4535 seconds.