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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=-16t^2+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.

0= -16t + 122t +99;  8.4 s
0= -16^2 + 99t + 122;  0.7 s
0= -16t^2 + 99t + 122; 8.4 s
0= -16t^2 + 122t + 99; 0.7 s

Respuesta :

MrEquation
The correct answer is the first choice.

The correct equation would be:  0 = -16t^2 + 122t + 99
The 122 goes in the middle because it is the initial velocity. The 99 goes at the end because it is the height.

If you use the quadratic equation, you will get values of -0.7 and 8.4. Only the 8.4 makes sense in this problem.

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