Module 2: Radical Functions

 

Radical functions can be written as having a vertical stretch or a horizontal stretch. In Try This 4 you looked at the radical functions  and  and discovered that the graphs of these two functions are the same. When you look at the functions, you can see how the second function can be rearranged to be the same as the first function.

 

 



You can compare these functions to the function  and describe the function  as having a vertical stretch by a factor of 2.

 

The functions y equals square root of x and y equals 2 times square root of x are graphed. The vertical distance from the function to the x-axis are highlighted from the point (16, 4) on the function y equals square root of x and on the point (16, 8) on the function y equals 2 times square root of x.

 

When you compare  to  you can describe the transformation as a horizontal stretch by a factor of

 

The functions y equals square root of x and y equals square root of 4x are graphed. The horizontal distances from the function to the y-axis are highlighted from the point (16, 4) on the function y equals square root of x and on the point (4, 4) on the function y equals square root of 4x.

 

Even though the stretches are different, the resulting graphs are the same. Note: When analyzing radical functions, any stretch can be described as either a vertical stretch or a horizontal stretch.

 

Self-Check 3
  1. Consider the function
    1. Describe the transformation represented by f(x) as compared to  Answer
    2. Write a function equivalent to f(x) in the form  Describe the transformation represented by g(x) as compared to  Answer
    3. Graph both functions f(x) and g(x). How do the graphs compare? Answer

Up to this point, you have graphed radical functions using transformations. Now you will look at a graph and determine the radical function. View Determining a Radical Function from a Graph, which shows an example of how to write the radical function from a graph.

 

 

This is a play button that opens Determining a Radical Function from a Graph.



textbook

If you would like to see another example of determining a radical function from a graph, read through “Example 3” on pages 68 and 69 in the textbook.

 

Self-Check 4
  1. Complete parts a and b of “Your Turn” on page 69. Answers
  2. Complete question 14 on page 75. Answers