Use the quadratic formula to solve the equation.

If necessary, round to the nearest hundredth.

A rocket is launched from atop a 99-foot cliff with an initial velocity of 122 ft/s. a. Substitute the values into the vertical motion formula h = - 16t2 + vt + c. Let h = 0. b. Use the quadratic formula find out how long the rocket will take to hit the ground after it is launched. Round to the nearest tenth of a second.

A. 0 = - 16t2 + 99t + 122; 8.4 s B. 0 = - 16t2 + 99t + 122; 0.7 s C. 0 = - 16t2 + 122t + 99; 8.4 s D. 0 = - 16t2 + 122t + 99; 0.7 s

Question

Mathematics

Nehemiah Bailey

3 October, 14:01

Use the quadratic formula to solve the equation.

If necessary, round to the nearest hundredth.

A rocket is launched from atop a 99-foot cliff with an initial velocity of 122 ft/s. a. Substitute the values into the vertical motion formula h = - 16t2 + vt + c. Let h = 0. b. Use the quadratic formula find out how long the rocket will take to hit the ground after it is launched. Round to the nearest tenth of a second.

A. 0 = - 16t2 + 99t + 122; 8.4 s B. 0 = - 16t2 + 99t + 122; 0.7 s C. 0 = - 16t2 + 122t + 99; 8.4 s D. 0 = - 16t2 + 122t + 99; 0.7 s

+5

Answers (2)

Know the Answer?

Brynn Morgan · Answer 1

The formula is - 16t^2 + 122t + 99

Solving for t gives t = 8.36 seconds

Its C

Kasey Sullivan · Answer 2

When you put the given numbers (v=122, c=99) into the vertical motion formula, you get

0 = - 16t² + 122t + 99

Solving that using the quadratic formula for a=-16, b=122, c=99, you get

t = (-b±√ (b²-4ac)) / (2a)

t = (-122 ±√ (122²-4· (-16) ·99)) / (2· (-16))

t = (122 ±√21220) / 32

t = 3.8125 ± √20.72265625

t ≈ - 0.7 or 8.4

The appropriate choice is ...

C. 0 = - 16t² + 122t + 99; 8.4 s