<PRE><B>Question 134746</B>
The concentration of a drug in medical patients bloodstream is given by 
f(t)=5/(t^2+1)  where t is greater than or less than 0 is in hours and f(t) is in milligrams per liter. 
a. Does the concentration of the drug increase or decrease? Justify answer
As t increases, concentration decreases; they are indirectly related.
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b. The patient should not take a second dose until the concentration is below 1.5 milligrams per liter. How long should the patient wait before taking a second dose?
1.5 = 5/(t^2+1)
1.5t^2 + 1.5 = 5
1.5t^2 = 3.5
t^2 = 2.3333
t = 1.5275
He should wait at least 1.5275 hours.
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Cheers,
Stan H.
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