A projectile that is fired vertically into the air with an initial velocity of 120 ft per second can be modeled by the equation s=120t-16t.In the equation, s is the distance in feet of the projectile above the ground after t seconds.How long will it take for a projectile to reach 216 feet?

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Answers

2014-08-08T18:10:04+08:00
I assume the equation is S = 120T - 16T^2, so we substitute the distance to find T: 216 = 120T - 16T^2 --> 16T^2 - 120T + 216 = 0 --> 8(T - 3)(2T - 9) = 0 --> T = 3 seconds and 4.5 seconds.
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