Question

Can someone help me with this

Answer 1

Step-by-step explanation:

it is still precisely the same method and formula just with different numbers.

y = -16x² + 212x + 139

we assume, the ground is at 0 ft.

so, we need to solve

0 = -16x² + 212x + 139

the general solution for such quadratic equations is

x = (-b ± sqrt(b² - 4ac))/(2a)

in our case

a = -16

b = 212

c = 139

x = (-212 ± sqrt(212² - 4×-16×139))/(2×-16) =

= (-212 ± sqrt(44944 + 8896))/-32 =

= (-212 ± sqrt(53840))/-32

x1 = (-212 + 232.0344802...)/-32 = -0.626077506... s

x2 = (-212 - 232.0344802...)/-32 = 13.87607751... s

again, the negative solution for time did not make any sense, so, x2 is our solution.

the rocket will hit the ground after about 13.88 seconds.