Question

A rocket is launched from a tower. The height of the rocket, y in feet, is related to the

time after launch, x in seconds, by the given equation. Using this equation, find the
time that the rocket will hit the ground, to the nearest 100th of second.
y = -16x2 + 247x + 141

Answer 1

Answer: 15,99s

when the rocket hit the ground => y = 0

=> -16x² + 247x + 141 = 0 (*)

a = - 16 b = 247 c = 141

Δ = b² - 4ac = 247² + 16.4.141 = 70033 > 0 => (*) has 2 solutions

=> x =
`(247-√(70033) )/(32)=-0,55(removed)`

or x =
`(247+√(70033) )/(32)=15,99(s)`

Explanation: