Chapter 1 - Functions and Limits - 1.5 The Limit of a Function - 1.5 Exercises - Page 60: 10

$\lim\limits_{x \to 12^-}$f(t) = 150 $\lim\limits_{x \to 12^+}$f(t) = 300 The significance of the one-sided limits is that they show that the amount of drug in the patient's bloodstream begins decreasing the instant it enters the bloodstream. That is why there are holes in the graph.

Look and see what happens to y as x goes to 12 from the left hand side. From the graph, we can see that y goes to 150. Look and see what happens to y as x goes to 12 from the right hand side. From the graph, we can see that y goes to 300.