SOLUTION: Phone was thrown from top of a building. The height h(t) of the cell phone at time (t) is described by the function h(t) = -16tsquared +96t+112. When will the phone be at a heigh

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 Question 321711: Phone was thrown from top of a building. The height h(t) of the cell phone at time (t) is described by the function h(t) = -16tsquared +96t+112. When will the phone be at a height of 192 feet and how many seconds will it take to hit the ground? I have tried putting the numbers in and just cannot figure this out. Can you help please? ThanksAnswer by ankor@dixie-net.com(15652)   (Show Source): You can put this solution on YOUR website!Phone was thrown from top of a building. The height h(t) of the cell phone at time (t) is described by the function h(t) = -16tsquared +96t+112. When will the phone be at a height of 192 feet and how many seconds will it take to hit the ground? : -16t^2 + 96t + 112 = h(t) The phone will be at 192 ft when h(t) = 192 -16t^2 + 96t + 112 = 192 Subtract 192 from both sides -16t^2 + 96t + 112 - 192 -16t^2 + 96t - 80 = 0; a quadratic equation Simplify, and change the signs, divide each term by -16 t^2 - 6t + 5 = 0 Factors to (t - 5)(t + 1) = 0 The positive solution t = 5 sec , tel at 192 ft : Phone will hit the ground when h(t) = 0 -16t^2 + 96t + 112 = 0 Simplify again, divide by -16 t^2 - 6t - 7 = 0 Factors to (t - 7)(t + 1) = 0 positive solution t = 7 sec, phone strikes the ground