In Exercises 18, find the sum of the series.
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Textbook Solutions for Calculus: Single Variable
Question
Cephalexin is an antibiotic with a half-life in the body of 0.9 hours, taken in tablets of 250 mg every six hours. (a) What percentage of the cephalexin in the body at the start of a six-hour period is still there at the end (assuming no tablets are taken during that time)? (b) Write an expression for Q1, Q2, Q3, Q4, where Qn mg is the amount of cephalexin in the body right after the nth tablet is taken. (c) Express Q3, Q4 in closed form and evaluate them. (d) Write an expression for Qn and put it in closed form. (e) If the patient keeps taking the tablets, use your answer to part (d) to find the quantity of cephalexin in the body in the long run, right after taking a tablet.
Solution
The first step in solving 9 problem number 80 trying to solve the problem we have to refer to the textbook question: Cephalexin is an antibiotic with a half-life in the body of 0.9 hours, taken in tablets of 250 mg every six hours. (a) What percentage of the cephalexin in the body at the start of a six-hour period is still there at the end (assuming no tablets are taken during that time)? (b) Write an expression for Q1, Q2, Q3, Q4, where Qn mg is the amount of cephalexin in the body right after the nth tablet is taken. (c) Express Q3, Q4 in closed form and evaluate them. (d) Write an expression for Qn and put it in closed form. (e) If the patient keeps taking the tablets, use your answer to part (d) to find the quantity of cephalexin in the body in the long run, right after taking a tablet.
From the textbook chapter SEQUENCES AND SERIES you will find a few key concepts needed to solve this.
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