00:01
In this problem, f of t is in order by the amount of morphine in the body.
00:09
T hours at t hours from the beginning of the infusion.
00:17
So for part a, given that the body removes the drug at a rate proportional to the amount of the drug present in the body, the constant of proportionality will be k being equal to 0 .35.
00:33
So the french equation, dfdt will be equal to negative 0 .35 times f.
01:03
And the initial will be zero.
01:15
So at any, so at the end time, the morphine will be rejected as an increasing rate of t milligrams per hour.
01:28
So therefore we have dfdt is equal to negative.
01:41
0 .35 f plus t for part b if the infusion lasts for over eight hours then the amount of morphing in the body during the infusion will be f of eight so we can now solve the differential equation for f of t which is this essentially but just changing it to y d y d t again as in previous these lessons we're going to multiply both sides of the de by the integrating factor integrating factor being e to the 0 .35 t now we could integrate both sides again you could use integration by part to solve this so you have e to the 0 .35t times y would be equal to c to the c times e to the 0 .35t plus e to the 0 .35t over the square root of 0 .35 square plus a constant c, e to the negative 0 .35 times t.
06:56
Here you have this 0 .35, chance, out with this...