Algebra and Up:
Question: Rico throws a football into the air. The football's height above the ground in meters after a given amount of time in seconds t can be found using the function f(t) = –5t² + 15t + 2. How long does the football stay in the air after Rico throws? You may use your calculator. Round your answer to the nearest tenth of a second.
Answer: 3.1 seconds
Solution: To find the amount of time the ball stays in the air, we find the values of t that put the ball 0 feet above the ground by solving for f(t) = 0. We can use the quadratic formula and our calculators to find that when –5t² + 15t + 2 = 0, t can be either a negative value or ~3.1279... seconds. So, the ball is in the air for approximately 3.1 seconds.
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