# TI-82 Graphing Calculator Supplement

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The TI-82 calculator is very powerful and can greatly simplify mathematical calculations with some of the internal commands.

There are two major differences most people will find when working with the TI-82 graphing calculator over a scientific calculator. The first is that no command is executed until you press the ENTER key. On a regular calculator, numbers are changed as you hit each operation, on the graphing calculator, nothing is calculated until the end. This allows you to go back and make corrections before it's too late. The second is the order the keys are pressed. On the TI-82, the commands are entered as you would write them (left to right). For example, to find the square root of 6, you type 2nd x2 6 ENTER. On a typical scientific calculator, the sequence would be 6 2nd x2.

The following will explain some of the keys which will be used in this class which are different from a normal calculator.

The 2nd key gives access to all the commands which are contained in blue above each key.

The ALPHA key gives access to the letters and symbols in white located above each key. These can be used as variables in conjunction with the STO and RCL keys which act as the memory keys to store and recall values.

The 2nd (-) key will give the value of the last calculation. It appears on the screen as Ans. On a normal scientific calculator this wasn't necessary since the operations were always performed on the answer shown. However, because of the way the TI-82 works, it may be necessary to use this key.

The ^ key will raise a quantity to a power. It takes the place of the y^x or x^y key on most calculators.

The x-1 key is located on the far left of the keyboard and will find the inverse of a quantity. When used on a real number it is like the 1/x or reciprocal key on most calculators. However, it can also be used to find the inverse of a matrix.

There are two keys which look like minus keys, yet they are very different and cannot be interchanged. There is the unary operator, opposite or negative, (-) key. It is gray and located to the left of the ENTER key. The binary operator, subtraction, - key is blue and located above the + key. The first is only used to take the opposite of a single quantity, the second must have a quantity before it and a quantity after it, and it finds the difference between the two. If you get an ERR:SYNTAX error from the calculator, this is the first thing you should check.

The MATH key is located on the far left of the calculator. The first option under the MATH key is FRAC. This is a very important key because your instructor firmly believes that fractions are your friend and instead of giving an answer like 0.962962963, you should give an answer like 26/27. Since FRAC is the first option, all you have to do is hit ENTER twice (once to accept the FRAC command and once to execute it). Get used to the sequence MATH ENTER ENTER, you will be using it frequently.

The MATH key contains the cube and cube roots keys, as well as the xth root of y key.

Also under the MATH key is the PRB menu (Probability). This gives up the ability to do factorials !, Permutations nPr, and Combinations nCr.

The ENTRY key is obtained by pressing 2nd ENTER. You may scroll through the last ten (10) expressions entered by repeating the ENTRY key. This is extremely useful as you can go back and change a single number in a complex expression with out having to retype the entire thing.

QUIT is found by pressing 2nd MODE. This will get you out of certain operations (such as entering a matrix).

CLEAR will erase the current line of input. If you just want to totally start over entering an expression, this is the key that will do it. It will also back you out of any of the TI-82's native menus (as opposed to a program which has a menu - you will have to hit ON which acts as a break to get out of user program menus).

There are other features of the calculator which we will be using in this class. We will cover these at a future time. You will probably want to take your manual and read through some of it. If you are in College Algebra, concentrate on the graphing and matrices sections; Finite Math students should concentrate on the matrices; and Statistics students should concentrate on the statistics section of the manual.

## Useful Programs by Course

### Calculus

These programs are ran by pressing the PRGM key and then arrowing to the program name and pressing ENTER

Whenever a list is called for, it must be enclosed in braces {} and the items separated by commas. See how to work with lists on the TI-82.

Several of the matrix programs require that the matrix being operated on be as Ans. This just means that you need to have the last thing on the screen the matrix that you want to use. This is necessary because many of the matrix programs build on the last operation to do the next. You can run the next phase by just pressing ENTER.

Depending on the course you are in, your instructor may not have provided you with all of the above programs.