Half life question in matlab

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Bob 2015-1-29

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评论： noor iraq 2020-5-10

Metronidazole (used to treat infections) has a half life of H = 7.9 hours. Use solve to calculate [5 pt] the amount of time it takes for 50mg to decay to 20mg. Note that the decay constant is −ln(2)/H.

Can someone help me with the code that would be used to solve this type of problem?

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Star Strider 2015-1-29

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See the documentation for the solve function. The question itself has all the information you need otherwise. Particularly note ‘−ln(2)/H’.

The question assumes single-compartment kinetics for metronidazole, an anti-protozoal agent that is also active against C. dificile and some others.

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Star Strider 2015-1-30

在 MATLAB Online 中打开

For the record, the solution to this problem is quite simply:

syms C(t)
H = 7.9;
K = -log(2)/H;
C(t) = exp(K*t);
t20s = solve(C == 20/50, t);
t20d = vpa(t20s, 3)

giving:

t20d =
10.4

So the concentration has reached the 20mg level at 10.4 hours.

noor iraq 2020-5-10

And if it with its Graph ?

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Roger Stafford 2015-1-29

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Bradley, just ask yourself, "what power of 2 do I have to divide 50 by to get 20?". Then that power should be the ratio of the necessary decay time to 7.9 hours. It would be a very simple one-line matlab computation.

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Bob 2015-1-29

编辑：Bob 2015-1-29

so that would be 20 because 20^2 then divide that by 20 which gives you 20. So I have this: solve(7.9*(-log(2)/(log(50/20)))). But I am getting an error because I don't have a variable. Would I replace 7.9 with x?