Chapter 4.6, Problem 16E

Solution

To graph : The function $y=\cos \left|x\right|$ showing four periods and its domain and range.

Given information :

The function $y=\cos \left|x\right|$

Graph :

Domain:

The domain of $f\left(x\right)$ is the set of all those real numbers for which $f\left(x\right)$ is meaningful.

Range:

Range of a real number of a real variable is the set of all real values taken by $f\left(x\right)$ at points in its domain.

The function is $y=\cos \left|x\right|$ .

Graph the above equation in the viewing window $\left[-2\pi ,2\pi \right]\text{ by}\left[-5,5\right]$ .

  

Hence, it is evident from the graph that for all the values of $x$ , the function is defined. Thus, the domain of the function is $x\in \left(-\infty ,\infty \right)$ .

And, from the graph it is observed that the function assumes all the values between $-1\text{ and 1}$ , including these two numbers. Thus, the range of the function is $y\in \left(-1,1\right)$ .

Interpretation :

The domain of the function is $x\in \left(-\infty ,\infty \right)$ .

The range of the function is $y\in \left(-1,1\right)$ .