Answer:
Step-by-step explanation:
To determine the time when the height is 40 meters above the ground, we would substitute 40 for h in the given equation. It becomes
1.2 + 4t0t - 5t² = 40
5t² - 40t + 40 - 1.2 = 0
5t² - 40t + 38.8 = 0
The general formula for solving quadratic equations is expressed as
x = [- b ± √(b² - 4ac)]/2a
From the equation given,
a = 5
b = - 40
c = 38.8
Therefore,
t = [- - 40 ± √(- 40² - 4 × 5 × 38.8)]/2 × 5
t = [40 ± √(1600 - 776)]/10
t = [40 ± √824]/10
t = (40 + 28.71)/10 or x = (40 - 28.71)/10
t = 6.871 seconds or t = 1.129 seconds
