How to Use a Graphing Calculator

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A graphing calculator is a powerful instrument that does a lot more than merely add, subtract, multiply and divide numbers. These machines are, nowadays, not so much calculators as they are hand-held computers, similar to cell phones or tablets but with the specific purpose of helping you solve math problems, some of them quite complex.

Perhaps the most important of a graphing calculator's capabilities is its graphing tools. It is possible to both generate a graph given an equation or a set of data points, or use a provided graph to derive the equation and data associated with that graph.

The instructions here apply to TI-83 and TI-84 models, but non-Texas Instruments calculators operate in a very similar way.

Basic Graphing Functions

  1. Press the "Y=" button to enter the function screen.
  2. Enter the function (e.g., Y = X2 - 4) into one of the lines.
  3. Press "GRAPH." The calculator will draw the function for you.     

To find the Y-intercept of a graph that has been drawn:

  1. Press "2nd," then "TRACE" to go to the "CALCULATE" window.
  2. Highlight "value" and press "ENTER."
  3. At the bottom of the screen that appears, enter "0" after "X=." The result will be the Y-intercept and associated X-coordinate.

Non-Linear and Linear Regressions

  1. Press "2nd," and then "STAT PLOT." Press "ENTER."
  2. After clearing all functions in "Y=", input data in L1 and L2.
  3. Graph the data points by going to "9: ZOOM STat."
  4. Look at "CALC" and choose a regression from the list.
  5. Choose "9: ZoomSTat" to view data with a regression curve.

Quadratic Equations

  1. Press the "Y=" button to enter the function screen.
  2. Enter the function; for example, "−3x2+14x−8."
  3. Press "2nd," then "TRACE" to go to the "CALCULATE" window.
  4. Select whether the vertex is a maximum (as in this example) or a minimum.
  5. Using the arrows, select the LEFT BOUND and the RIGHT BOUND to get the vertex coordinates.
  6. Repeat the process to find the X-intercept or intercepts, if desired. It may be necessary to ZOOM out.

References

About the Author

Kevin Beck holds a bachelor's degree in physics with minors in math and chemistry from the University of Vermont. Formerly with ScienceBlogs.com and the editor of "Run Strong," he has written for Runner's World, Men's Fitness, Competitor, and a variety of other publications. More about Kevin and links to his professional work can be found at www.kemibe.com.

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