SOLUTION: the function D(h)=7e^-0.3h can be used to find the number of milligrams D of a certain drug that is in a patient's bloodstream h hours after the drug has been administered. a.

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Question 1129811: the function D(h)=7e^-0.3h can be used to find the number of milligrams D of a certain drug that is in a patient's bloodstream h hours after the drug has been administered.
a. how many milligrams will be presented after 2 hours?
b. when the number of milligrams reaches 1, the drug is to be administered again. in how many hours will the drug need to be administered again?
Answer by josgarithmetic(39621) About Me  (Show Source):
You can put this solution on YOUR website!
D%28h%29=7e%5E%28-0.3h%29

h if D(h)=1:

ln%28D%29=ln%287e%5E%28-0.3h%29%29
ln%28D%29=ln%287%29-0.3h%2Aln%28e%29
-0.3h=ln%28D%29-ln%287%29
h=%28-1%2F0.3%29%28ln%28D%29-ln%287%29%29
substitute
h=%28-1%2F0.3%29%28ln%281%29-ln%287%29%29
h=%281%2F0.3%29%28ln%287%29-ln%281%29%29
highlight%28h=6.5%29
6 hours 30 minutes
OR
6%261%2F2hours