Question

factoring
question id: 1799505
the achievement of the progress bar may be uneven because questions can be worth more or less (including zero) depending on your answer.
a stone is launched into the air from a height of 384 feet. the height, h, of the stone, in feet, t seconds after launch is given by the formula h = -16t² + 32t + 384. after how long will the stone hit the ground?
-4 seconds
6 seconds
4 seconds
12 seconds

Explanation:

Step1: Set height to 0

$0 = -16t^2 + 32t + 384$

Step2: Simplify equation

Divide by -16: $t^2 - 2t - 24 = 0$

Step3: Factor quadratic

$(t - 6)(t + 4) = 0$

Step4: Solve for t

$t = 6$ or $t = -4$ (time can't be negative)

Answer:

6 seconds