College Algebra & Trigonometry, 2018a

148 CHAPTER 3. EXPONENTS AND LOGARITHMS
If we turn the graph around by changing x to −x in the formula, then we will be
working with the decaying tail of the graph:
20
15
10
y =2 −x
5
−4 −2 2 4
−5
Let’s zoom in on the portion of the graph in the Quadrant I:
1.5
1
0.5
y =2 −x
−1 1 2 3 4 5
−0.5
The behavior shown in the graph is quite useful for modeling radioactive decay,
processes of heating and cooling, and assimilation of medication in the bloodstream.
Let’s look at an example.