Graphing with Excel

by Zack Kroll

Construct a graph of any function y = f(x) by generating a table of values with the x values in one column and the y values.

Excel is program that most people are familiar with, but may shy away from when it comes to looking at mathematics. At one point in time it was one of the most sophisticated software programs, especially when dealing with spreadsheets. These days there are so many different types of software and applets that allow us to do perform a variety of different sorts of tasks.

We decide to look at linear, cubic, sine and cosine functions.

Interval: (1, 20)

For this graph we decide to restrict the domain of our function to from x values 1 to 20. This linear function and graph is the type of graph that could be used in a middle school classroom when students first begin to examine the idea of rate of change and slope.

Interval: (-10, 10)

The difference betwen this graph and the one above is the domain: -10 to 10. Here we are able to see the y-intercept as well as all four quadrants. In the Common Core Georgia Performance Standards, students learn about slope and graphing lines in 8th grade. Excel could be a great tool for them to use when collecting data or simply graphing linear functions.

Interval: (1, 20)

This is an example of a cubic function graphed in the first quadrant. There are some powerful real world examples that teachers can use in order to get students to better understand exponents and exponential growth. Through Excel students can examine data and determine how quickly something grows or declines.

Interval: (-10, 10)

This graph represents a more traditional approach to looking at cubic functions. Students can see the graph of y = x^3 over an interval that contains positive and negative x values. This allows them to explore the relationship that occurs between the x and y values due to working with an odd numbers exponent. Although it is not pictured here, the teacher could also look at the difference between y = x^2 and y = x^3. How do the graphs of those two functions differ over the same interval? Why do their graphs look so much different?

Intervals: (-10, 10)

The last two functions that we examine are trigonometric functions, specifically that of sine and cosine. Compared to other software programs and applets Excel does not do as great of a job of displaying the graphs of trigonometric functions. What it does allow the viewer to see, though, is how the y values change cooresponding to the graphs. This can be a powerful tool that a teacher can use to help students better understand these functions in high school.

These are just a few of the functions that Excel is able to graph. Its ability to do so depends a great deal on the willingness of the user to explore the options that are out there.