Chapter 3.1, Problem 26E

Solution

a.

To match: the given function with its graph.

Graph (d)

Given information:

The given function is $y=2^{-x}$ .

The given graphs are:

1. 
2. 
3. 
4. 
5. 
6. 

Explanation:

Graph the given function using Ti-83 calculator,

First pressand enter the function as shown:

  

Then press and set the window as shown:

  

Lastly press and this gives the required graph.

  

This graph matches with the graph (d).

b.

To match: the given function with its graph without using grapher.

Graph (d)

Given information:

The given function is $y=2^{-x}$ .

The given graphs are:

1. 
2. 
3. 
4. 
5. 
6. 

Explanation:

Consider the given function,

  $y=2^{-x}$

Here, it can be observed that at $x=0$, the value of this function is:

  $y=2^{-0}=1$

The only graphs for which this is true are graphs (a) and (d). So, all other choices are eliminated.

Now, check what happens to function as x becomes extremely large positive number and as x becomes extremely large negative number

  $\begin{array}{l}\underset{x\to \infty }{\lim }{2}^{-x}=0\\ \underset{x\to -\infty }{\lim }{2}^{-x}=\infty \end{array}$

The only graph with this behavior is graph (d).