1. Common Errors There are a number of errors that are repeatedly encountered using a graphing calculator. Being aware of the possibilities can save much time and frustration. Error #1: Using the minus and negative keys incorrectly. The minus key (blue key above + sign) is used after a number or variable for the operation of subtraction. The negative key (bottom row, inside parenthesis) is used in front of a number or variable for opposite value.

2. Slide 2 Common Errors Enter the following on the home screen to see the difference between the two keys. (1) Enter 5 - 3 (minus key) and press ENTER. (2) Enter 5 (-) 3 (negative key) but don’t press ENTER yet. (3) Note the difference in size, the minus being the larger. Also, the negative is raised slightly higher than the minus.

3. Slide 3 Common Errors (4) Now press ENTER... and an error results. (5) Enter a 2, to select Goto, and the calculator locates the error. Goto can be very helpful in locating problems. Note that the blinking cursor goes straight to the negative sign, which is exactly where the error was located.

4. Slide 4 Common Errors Some of the uses for the negative are... (2) setting the WINDOW (1) entering − 5 − 3 (the negative in front of the 5)   (3) entering equations 

5. Slide 5 Common Errors Error #2: Getting an error when trying to graph a function. The error may relate to the use of minus and negative as discussed in error #1. It is important to also recognize that sometimes you may not get an error screen, but the graph is clearly incorrect. The problem could be an incorrect use of a negative.

6. Slide 6 Common Errors Sometimes the error is simply having a STAT PLOT turned on. This is easily corrected by going to STAT PLOT|PlotsOff. When PlotsOff appears on the home screen, press ENTER, and try the graph again.

7. Slide 7 Common Errors Error #3: Not seeing that a value is given in scientific notation. On a graphing operation, the bottom of the screen may be showing x = 3.2781419E-9, where x = 0 was expected. Recognizing that E-9 means multiply by 10 -9, or a value every close to zero, makes sense of what might have first appeared to be a value around 3.278.

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