A patient is injected with a drug every 12 hours. Immediately before each injection the concentration of the drug has been reduced
by 90% and the new dose increases the concentration by 2.4 mg/L.
(a) What is the concentration after three doses?
—————mg/L

(b) If Cn is the concentration after the nth dose, find a formula for Cn as a function of n.
Cn=——————-

(c) What is the limiting value of the concentration?
—————mg/L