## Articles From Jeff McCalla

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Article / Updated 06-06-2023

You bought the TI-84 Plus C graphing calculator to help you do graphs, and help you it does. The points in the following list walk you through the steps to take to get your TI-84 Plus C to display a graph:

View ArticleCheat Sheet / Updated 10-21-2022

The TI-84 Plus CE graphing calculator is one of the most popular calculators in the world. Find out the important keystrokes you need to know to use the TI-84 Plus, and learn the math functions and constants that the TI-84 Plus CE makes available to you. Get to know the basics of graphing on your TI-84 Plus CE, as well as how to use the calculator’s zoom commands and special menus.

View Cheat SheetArticle / Updated 10-19-2022

The letters STO may look like texting language, but the TI-84 Plus calculator's STO key is a handy feature to have around. If you plan to use the same number many times when evaluating arithmetic expressions, consider storing that number in a variable. To do so, follow these steps: If necessary, press [2nd][MODE] to enter the Home screen. Enter the number you want to store in a variable. You can store a number or an arithmetic expression. Press The result of this action is shown in the first screen. Press [ALPHA] and press the key corresponding to the letter of the variable in which you want to store the number. The letters used for storing variables are the letters of the alphabet and the Greek letter theta. Press [ENTER] to store the value. This is illustrated in the second screen. Insert your stored variable into an expression After you have stored a number in a variable, you can insert that number into an expression. To do so, place the cursor where you want the number to appear, press [ALPHA], and press the key corresponding to the letter of the variable in which the number is stored. See the third screen. The number you store in a variable remains stored in that variable until you or the calculator stores a new number in that variable. Because the calculator uses the letters X, T, and the Greek theta when graphing functions, parametric equations, and polar equations, it is possible that the calculator will change the value stored in these variables when the calculator is in graphing mode. For example, if you store a number in the variable X and ask the calculator to find the zero of the graphed function X2, the calculator will replace the number stored in X with 0, the zero of X2. So avoid storing values in these three variables if you want that value to remain stored in that variable after you have graphed functions, parametric equations, or polar equations.

View ArticleArticle / Updated 10-19-2022

Before you can graph a function on your TI-84 Plus calculator, you must enter it into the calculator. The calculator can handle up to ten functions at once, Y1 through Y9 and Y0. To enter functions in the calculator, perform the following steps: Press [MODE] and put the calculator in Function mode. To highlight an item in the Mode menu, use the keys to place the cursor on the item and then press [ENTER]. Highlight FUNCTION in the fourth line to put the calculator in Function mode. See the first screen. Press ! to access the Y= editor. See the second screen. Enter your function. If necessary, press [CLEAR] to erase a previous function entry. Then enter your function. Your math textbook may use a function notation like this: f(x)=2x+1. To graph a function in your calculator, you must realize f(x) is interchangeable with y, only the notation differs. See the third screen. When you’re defining functions, the only symbol the calculator allows for the independent variable is the letter X. Press to enter this letter in your function. As a timesaver, when entering functions in the Y= editor, you can reference another function. Use the shortcut Y-VAR menu to paste a function name in the function you’re entering in the Y= editor. Just press [ALPHA][TRACE] and choose the name of the function you want to insert in your equation. See the first screen. How does calling up the name of another function save you time? Well, say you’re trying to graph a circle in your calculator with the equation x2 + y2 = 36. Of course, you need to solve the equation for y to graph the circle equation in your calculator. Solving for y gives you: Notice, it takes two functions to graph a circle! No problem. In function Y1 enter Then, to save time, use the shortcut Y–VAR menu to enter Y2 = –Y1. See the second screen.

View ArticleArticle / Updated 10-19-2022

After you have entered functions into the TI-84 Plus calculator and formatted your graph, you’re almost ready to start your graphing fun. Once you get the hang of graphing, you won’t need to go through all these steps. Turning off Stat Plots (if necessary) The top line in the Y= editor tells you the graphing status of the Stat Plots. If Plot1, Plot2, or Plot3 is highlighted, then that Stat Plot will be graphed along with the graph of your functions. If it’s not highlighted, it won’t be graphed. In the first screen, Plot1 is highlighted and will be graphed along with the functions in the Y= editor. To turn off a highlighted Stat Plot in the Y= editor, use the keys to place the cursor on the highlighted Stat Plot and then press [ENTER]. See the second screen. The same process is used to highlight the Stat Plot again in order to graph it at a later time. When you’re graphing functions, Stat Plots can be a nuisance if they’re turned on when you don’t really want them to be graphed. The most common symptom of this problem is the ERROR: INVALID DIMENSION error message — which by itself gives you almost no insight into what’s causing the problem. So if you aren’t planning to graph a Stat Plot along with your functions, make sure all Stat Plots are turned off! Selecting and deselecting a function on the TI-84 Plus Deselect (turn off) Y1 and Y2 by removing the highlight from their equal signs. This is done in the Y= editor by using the keys to place the cursor on the equal sign and then pressing [ENTER] to toggle the equal sign between highlighted and not highlighted. The calculator graphs a function only when its equal sign is highlighted! Do you see the difference between the two screens? Adjusting the TI-84 Plus graph window When you graph a function, you usually can’t see the whole graph. You are limited to viewing the graphing window, which typically shows only a small portion of the function. There are four values that determine the portion of the coordinate plane you can see: Xmin, Xmax, Ymin, and Ymax. Press [WINDOW] to display the current window variables. It takes practice to find a good viewing window for the function you’re graphing. Here are the steps needed to set the window of your graph: Press [WINDOW] to access the Window editor. After each of the window variables, enter a numerical value that is appropriate for the functions you’re graphing. Press e after entering each number. Entering a new window value automatically clears the old value. Make sure your (Xmin < Xmax) and (Ymin < Ymax) or you’ll get the ERROR: WINDOW RANGE error message. Editing your Window variables is a good place to start as you search for a good viewing window. In addition, using the Zoom features may be necessary to perfect your graphing window. The following gives an explanation of the variables you must set to adjust the graphing window: Xmin and Xmax: These are, respectively, the smallest and largest values of x in view on the x-axis. If you don’t know what values your graph will need for Xmin and Xmax, press [ZOOM][6] to invoke the ZStandard command. This command automatically graphs your functions in the Standard viewing window. Xscl: This is the distance between tick marks on the x-axis. (Go easy on the tick marks; using too many makes the axis look like a railroad track. Twenty or fewer tick marks makes for a nice looking x-axis.) If you want to turn off tick marks altogether, set Xscl=0 and Yscl=0. Ymin and Ymax: These are, respectively, the smallest and largest values of y that will be placed on the y-axis. If you have assigned values to Xmin and Xmax but don’t know what values to assign to Ymin and Ymax, press [ZOOM][0] to invoke the ZoomFit command. This command uses the Xmin and Xmax settings to determine the appropriate settings for Ymin and Ymax, and then automatically draws the graph. Yscl: This is the distance between tick marks on the y-axis. (As with the x-axis, too many tick marks make the axis look like a railroad track. Fifteen or fewer tick marks is a nice number for the y-axis.) Xres: This setting determines the resolution of the graph. It can be set to any of the integers 1 through 8. When Xres is set equal to 1, the calculator evaluates the function at each of the 133 pixels on the x-axis and graphs the result. If Xres is set equal to 8, the function is evaluated and graphed at every eighth pixel. Xres is usually set equal to 1. If you’re graphing a lot of functions, it may take the calculator a while to graph them at this resolution. If you change Xres to a higher number, your function will graph quicker, but you may not get as accurate of a graph. TraceStep and These two variables are linked together, and TraceStep is always twice as big as value, which determines how your cursor moves on a graph screen in “free trace.” TraceStep controls the X-value jump when you are tracing a function on a graph screen. Press [GRAPH] to graph the functions. Stopping or pausing your TI-84 Plus graph After pressing [GRAPH], there’s usually a small delay before you begin to see your function plotting on the graph from left to right. If it’s taking a long time for the calculator to graph your functions (maybe your Xres setting is too small), press [ON] to terminate the graphing process. Simply press [ENTER] to pause the plotting of your graph and then press [ENTER] again to resume graphing. See the following two screens. Notice, the elliptical busy indicator in the top right corner of the screen indicating that your calculator is working hard.

View ArticleArticle / Updated 10-19-2022

The functions housed in the Angle menu on your TI-84 Plus calculator enable you to convert between degrees and radians or convert between rectangular and polar coordinates. To convert degrees to radians, follow these steps: Put the calculator in Radian mode. Press [MODE], use the arrow keys to highlight RADIAN, and then press [ENTER]. If necessary, press [2nd][MODE] to access the Home screen. Enter the number of degrees. Press [2nd][APPS][1] to paste in the degree function. Press [ENTER] to convert the degree measure to radians. This is illustrated in the first screen. If you’re a purist who likes to see radian measures expressed as a fractional multiple of pi whenever possible, continuing with the following steps accomplishes this goal if it’s mathematically possible. To divide the radian measure by pi, press This is illustrated in the second screen. Press [MATH][ENTER][ENTER] to convert the result to a fraction, if possible. This is illustrated in the third screen. If the calculator can’t convert the decimal obtained in Step 6 to a fraction, it says so by returning the decimal in Step 7. To convert radians to degrees: Put the calculator in Degree mode. Press [MODE], use the arrow keys to highlight DEGREE, and then press [ENTER]. If necessary, press [2nd][MODE] to access the Home screen. Enter the radian measure. If the radian measure is entered as an arithmetic expression, surround that expression with parentheses. Press [2nd][APPS][3] to paste in the r function. Press [ENTER] to convert the radian measure to degrees. This is illustrated in the first screen. The TI-84 Plus is a complicated tool and it's easy to make mistakes on it. For more help, check out 10 Common Errors When Using the TI-84 Plus Calculator.

View ArticleCheat Sheet / Updated 02-17-2022

The TI-Nspire device is the most sophisticated handheld graphing calculator available, allowing users to display and evaluate values symbolically, and to reuse the same equations across multiple applications. Because it’s so sophisticated, navigating its features can sometimes be confusing. It helps to know a variety of methods of achieving your aims with the device.

View Cheat SheetStep by Step / Updated 01-26-2022

Even the best calculating machine is only as good as its input. This list identifies ten common errors made when using the TI-84 Plus calculator. Wouldn’t it be great to avoid some of the common errors that normally plague students who are using calculators?

View Step by StepCheat Sheet / Updated 01-21-2022

The TI-84 Plus C graphing calculator is one of the most popular calculators in the world. Find out the important keystrokes you need to know to use the TI-84 Plus, and learn the math functions and constants that the TI-84 Plus C makes available to you. Get to know the basics of graphing on your TI-84 Plus C, as well as how to use the calculator’s zoom commands and special menus.

View Cheat SheetVideo / Updated 11-19-2018

You can find the standard deviation of a data set in two ways with your TI-84 Graphing Calculator. First, have a look at the long lists to calculate the standard deviation from scratch on the TI-84 Graphing Calculator. Then see how to quickly find the standard deviation using one-variable stats. To help your understanding of standard deviation, this video explains what the abbreviations mean and where you can access these variables in your TI-84 Graphing Calculator. Most functions and commands that you use on the TI-84 Graphing Calculator are found in the menus housed in the calculator. Following is an overview of how to find and select menu items on the TI-84 Graphing Calculator. Accessing a TI-84 Plus menu Each menu on the TI-84 Graphing Calculator has its own key or key combination. For example, to access the Math menu, press [MATH]; to access the Test menu, press [2nd][MATH]. An example of a menu appears in the first screen. This is a picture of the Math menu. Some menus on the TI-84 Graphing Calculator, such as the Math menu, contain submenus. This is also illustrated in the first screen. This screen shows that the submenus in the Math menu are MATH, NUM, CMPLX, PROB, and FRAC (Math, Number, Complex, Probability, and Fraction). Use the keys to view the items on the other submenus. This is illustrated in the second and third screens. Scrolling a TI-84 Plus menu After the number 9 in the first two screens, a down arrow indicates that more items are available in the menu than appear on-screen. There’s no down arrow after the 4 in the third screen because that menu has exactly four items. To see menu items that don’t appear on-screen, repeatedly press the down-arrow key on your TI-84 Graphing Calculator: To get quickly to the bottom of a menu from the top of the menu, press the up-arrow key. Similarly, to quickly get from the bottom to the top, press the down-arrow key. Selecting TI-84 Plus menu items To select a menu item from a menu on the TI-84 Graphing Calculator, key in the number (or letter) of the item or use the keys to highlight the number (or letter) of the item and then press [ENTER]. Some menus, such as the Mode menu shown in the first screen, require that you select an item from a list of items by highlighting that item. The list of items usually appears in a single row and the TI-84 Graphing Calculator requires that one item in each row be highlighted. To highlight an item, use the keys to place the cursor on the item and then press [ENTER] to highlight the item. To access Catalog Help on the TI-84 Graphing Calculator, scroll to the menu item you want to use and press [+]. A screen showing the syntax of the command is displayed. Check out this guide of TI-84 Graphing Caluculator important keystrokes for more information.

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