0. Exponential Growth Functions Exponential Decay Functions b b>1 0 Type of function'>

Pearson Algebra 1 Common Core, 2011
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Pearson Algebra 1 Common Core, 2011 View details
7. Exponential Growth and Decay
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Exercise 36 Page 465

Start by writing properties of exponential growth and decay functions.

It is an exponential growth function.

Practice makes perfect

Let's start by writing properties of exponential growth and exponential decay functions, y=a* b^x. We assume a>0.

Exponential Growth Functions Exponential Decay Functions
b b>1 0
Type of function Increasing Decreasing
Domain All real numbers
Range All positive real numbers
Asymptote x-axis
Intercept (0,a)

With these in mind, let's write the properties of the given graph.

Window with a graph

We see that it

  • is an increasing function,
  • has an asymptote, x-axis, and
  • intercepts the y-axis at the point (0,5).

Additionally,

  • it seems that the point (- 1,2.5) lies on the curve and
  • the domain is all real numbers and the range is all positive real numbers.
We might assume that it is an exponential growth function. Then, since the y-intercept is the point (0,5), a is equal to 5. y=a * b^x ⇔ y=5 * b^x We know that the point ( - 1, 2.5) is on the curve. Let's substitute the point and find b.
y=5 * b^x
2.5=5 * b^(- 1)
â–Ľ
Solve for b
1/2=b^(- 1)
1/2=1/b
1* b=2 * 1
b=2
Now we can write the function. y=5 * b^x ⇔ y=5 * 2^x Let's draw its graph using calculator. we can enter it in the calculator by pushing Y= and writing the function.
Window with inequality

Next, by pushing GRAPH, the calculator will draw the graph of the function.

Window with a graph

We get the same graph. Therefore, the graph shows an exponential growth function.