Sometimes you are given the output value of a function and are asked to solve for the input value. The following example will show how to do this.

Example 2

Determine the x-value of the function «math style=¨font-family:`Times New Roman`¨ xmlns=¨http://www.w3.org/1998/Math/MathML¨»«mi»f«/mi»«mo»(«/mo»«mi»x«/mi»«mo»)«/mo»«mo»=«/mo»«mn»5«/mn»«mi»x«/mi»«mo»-«/mo»«mn»4«/mn»«/math» when «math style=¨font-family:`Times New Roman`¨ xmlns=¨http://www.w3.org/1998/Math/MathML¨»«mi»f«/mi»«mo»(«/mo»«mi»x«/mi»«mo»)«/mo»«mo»=«/mo»«mn»16«/mn»«/math».

Substitute 16 into the function in place of and solve for x.



 

Example 3

Graph the function .

Step 1: Create a table of values by choosing the x-values.

Step 2: Evaluate the function for the chosen inputs.

Step 3: Complete the table of values.

Step 4: Plot the ordered pairs as points on the graph and connect the points with a line.