00:01
The patient takes 150 milligrams of a drug at the same time every day.
00:05
And just before the tablet's taken, only 5 % of the drug remains in the body.
00:13
And then we'd like to know what quantity of the drug is in the body after the third tablet.
00:19
Or after the n tablet.
00:21
So for part a, we could even draw a picture for this.
00:30
So let qn just be the quantity in body after...
00:42
And tablets or in other words after 10 days so the quantity and of course this is in milligrams that's the units in case those are being stressed you can always point those out so here after the first day we'll get 150 and then after that we would have decreased all the way down to just only 5 % of that so 5 % of 150 that's just 150 over 20 15 over 20 15 over 2 and then after that right before we take the second tablet that's where we're at at 15 over 2 but then we take another tablet that's 150 so then we add 150 to this so that'll push us up to so we have this right here 7 and a half so then we would have jumped up to 157 .5.
02:09
And then we could do this one more time.
02:12
Then we would decrease to only 5 % of that.
02:17
And then we would add 150 to this.
02:21
So the value, so q1, when we take our first tablet, we have 150.
02:28
This value that we just found over here was q2 and then q3 will be 5 % of this and then we just add by 150 so you have in this case you can go ahead and simplify this add the fractions together and simplify to get your final answer but that's q3 so otherwise if a calculator is not needed just use the fraction if you have to get the decimal, go ahead and use a calculator.
03:16
That's just q3 and then let's go and write down the formula for qn...