Big Ideas Math Algebra 1, 2015
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Big Ideas Math Algebra 1, 2015 View details
7. Graphing Absolute Value Functions
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Exercise 27 Page 160

Create two tables of values and plot the graphs on the same coordinate plane.

Graph:

Comparison: See solution.

Practice makes perfect

To graph the functions without going through the entire process of transforming the parent function, we can make two tables of values. Then, we only need to plot and connect the obtained points and compare the graphs.

Graph

Let's begin with creating a table of values for f(x).

x |x-4| f(x)=|x-4|
-1 | -1-4| 5
1 | 1-4| 3
3 | 3-4| 1
Now we do the same with g(x).

x |3x-4| g(x)=|3x-4|
-1 |3( -1)-4| 7
1 |3( 1)-4| 1
3 |3( 3)-4| 5

Finally, we will plot and connect these ordered pairs. Keep in mind that the graph of an absolute value function has a V-shape!

Comparison

Note that we can rewrite g(x) in terms of f(x), because g is of the form y=f(ax). Looking at the functions we can see that a= 3. lf(x)=|x-4| g(x)=| 3x-4| ⇒ g(x)=f( 3x) The graph of g(x) is a horizontal shrink of the graph of f(x) by a factor of 1 3. The y-intercept is the same for both graphs. When the input value of f(x) is three times the input value of g(x), the output values of f(x) and g(x) are the same.