A baseball is hit from a height of 0.8 m. After “t” seconds, its height “h”, in metres, is given by the equation h = -5t2 + 20t + 0.8. How long does the ball stay at least 15 m above the ground?
What would be the LET statement?
Let
-5t2 + 20t + 0.8 > 15
5t^2 - 20t + 14.2 < 0
You know that y = 5t^2 - 20t + 14.2 is a parabola opening upwards
find the roots of 5t^2 - 20t + 14.2 = 0 , and the time will be the time between those two roots
The LET statement for this problem would be:
Let h = 15.
In order to determine how long the ball stays at least 15 m above the ground, we need to find the value(s) of "t" when the height "h" is equal to or greater than 15.
The LET statement stands for "Let h = 15" because we want to solve for the value(s) of "t" when the height is at least 15 m. By substituting the value of "h" in the given equation h = -5t^2 + 20t + 0.8 with h = 15, we can solve for "t" and determine the time in seconds when the ball reaches or exceeds a height of 15 m above the ground.