Question 603039
h(t)= -16t2 + 80t +73 
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-16t^2 + 80t+73 = -9
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-16t^2 + 80t + 82
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t = [-80 +- sqrt(80^2-4*(-16)*82)]/(-32)
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t = 5.8727 seconds
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Cheers,
Stan H.