Parametric Equations: Time Pt. 1

Question

Find the time it takes for a rocket following the path of the parametric equations, x = 4t - 8 and y = -2t^2 + 18, to hit the ground

Answer 1

Hitting the ground is the same as y=0. That is: -2t^2+18=0. Subsequently t^2=9 which yields: t=3.

Answer 2

y = 18 -2t^2 = 0

t^2 = 18/2 = 9

t = sqr9 = 3 seconds to hit the ground