Question 83686
The height h in feet of an object after t seconds is given by the function 
	h = –16t^2 + 70t + 5.  
How long will it take the object to hit the ground?
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When it hits the ground its height will be zero.
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-16t^2+70t+5=0
t = [-70+-sqrt(70^2-4*-16*5] / -32

t = [-70+-sqrt(5220)] / -32

t = [-70+-72.25] / -32

t = 4.44529... seconds
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Cheers,
Stan H.