Question

The height of a flare is given by the equation h(t)= -0.5t² +16t+22 where h is the height of the flare in metres and is the time the flare has been in the air in seconds. How long will the flare be in the air if it fizzles out at a height of 10 m above ground?

Answer 1

the flare will be in the air for approximately 29.09 seconds before fizzling out at a height of 10 meters above ground.

Explanation:

To find out how long the flare will be in the air, we need to find the time it takes for the flare to reach a height of 10 meters.

Setting h(t) to 10 and solving for t:

-0.5t² +16t+22 = 10

-0.5t² +16t+12 = 0

Using the quadratic formula:

t = (-b ± √(b² - 4ac)) / 2a

Where a = -0.5, b = 16, and c = 12:

t = (-16 ± √(16² - 4(-0.5)(12))) / 2(-0.5)

t = (-16 ± √(256 + 24)) / -1

t = (-16 ± √280) / -1

t ≈ -1.09 or t ≈ 29.09

Since time cannot be negative, we can ignore the negative root. Therefore, the flare will be in the air for approximately 29.09 seconds before fizzling out at a height of 10 meters above ground.