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January 21st, 2011, 02:00 PM   #1
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Help with differential equation problem

A person's weight depends on both the number of Calories consumed and the energy used. Moreover the amount of energy used depends on a person's weight - the average amount of energy used by a person is 17.5 Calories per pound per day. So, the more weight a person loses, the less energy a person uses (assuming the person maintains a Constant Level of activity). An equation that can be used to model weight loss is;

dw/dt = c/3500 - 17.5w/3500.

Where w, is the person's weight (in pounds), t is the time in days, and c is the constant daily consumption.

[a] Find the general Solution of the differential equation; dw/dt = c/3500 - 17.5w/3500.

My Answer:
Wolframalpha answer:

I don't what you mean by using e^(-0.005t) as an integrating factor.

[b] Consider a person who weighs 180 pounds and begins a diet of 2500 Calories per day. How long will it take the person to lose 10 pounds? How long will it take the person to lose 35 pounds?
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January 21st, 2011, 05:53 PM   #2
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Can you try solving the differential equation by using e^(.005t) as an integrating factor, and then post your work?
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