Solving Quadratic Equations
So I got this question:
Example 3: When a football is kicked with a vertical speed of 20m/s, its height, h
metres, after t
seconds is given by the formula:
How long after the kick is the football at a height of 15m?
Substitute 15 for h
in the formula:
This produces a quadratic equation. The solution of the equation gives the times when the height is 15m.
Collect all the terms on one side of the equation.
The football is at a height of 15m twice: first on the way up, 1 s after the kick, then on the way down, 3 s after the kick.
A baseball is hit with a vertical speed of 31.3m/s. Use the formula in the modelling box following Example 3. How long after being hit is the ball at a height of 25m? Give your answer to 1 decimal place.
How exactly do I form the equation? I got it but I don't think I'm on the right track. Thanks a bunch.