Question

A small toy rocket is launched from a 20-foot pad. The height (h, in feet) of the rocket t seconds after

taking off is given by the formula h = – 2t^2– 6t + 20. How long will it take the rocket to hit the
ground?

Answer 1

t = 2 sec

Explanation:

h = – 2t²– 6t + 20

When the rocket hits the ground. h = 0 ft.

– 2t²– 6t + 20 = 0 /: (-2)

t² + 3t - 10 = 0

(t + 5)(t - 2)=0

t = - 5, t = 2

Time can be only positive.