SOLUTION: A ball is thrown straight up from a rooftop 432 feet high. The formula below describes the ball's height above the ground, h, in feet, t seconds after it was thrown. The b
Question 1178634: A ball is thrown straight up from a rooftop 432 feet high. The formula below describes the ball's height above the ground, h, in feet, t seconds after it was thrown. The ball misses the rooftop on its way down. The graph of the formula is shown. Determine when the ball's height will be 378 feet and identify the solution as a point on the graph.
h=-16t^2+30t+432
To solve the problem and to get the answer, you need to solve this quadratic equation
-16t^2 + 30t + 432 = 378.
Rewrite it in this equivalent form
16t^2 - 30t - 54 = 0
Find the roots using the quadratic formula
t = = = .
Only positive root t = = = 3 seconds is the solution to the problem.
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