# Quadratic Equation: A Program For TI84 Calculators

Have you ever used Quadratic Formula? Do you have a programmable calculator? Have you wished there was an easier way to get the answers? If you answered "Yes!" then this instructable can help you. This Instructable will show you how to program your TI84 calculator to do Quadratic Formula for you. This program was born when my Calculus teacher and I wanted more information from the very basic Quadratic Formula program that we already had. He said that he would like to make a new one and so that's what happened.

*DISCLAIMER: IF YOU ONLY NEED A PROGRAM TO SOLVE QUADRATIC EQUATION BUT DO NOT NEED TO KNOW WHAT KIND OR SOLUTIONS ARE PRODUCED DO NOT USE THIS PROGRAM*

There are other Instructables that discuss quadratic equation programs. These will get the job done with no extras:

Quadratic Formula for the TI-83 and 84,

Program the Quadratic Formula on TI-83 or equivalent

Intro to Programming (Using a Calculator)
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## Step 1: Materials & Pre-Programming Checks

Required Materials:
Programmable Calculator
Patience
Time

Possibly Required Materials:
Computer
TI Connect
USB to mini USB cable

For the calculator I have a TI84 Plus Silver Edition. A regular TI84 or TI83 should work as well althoug I am not sure about how well a TI83 would work.

Before you begin there is something that you NEED to check and something that you SHOULD check. These things are the available memory on your calculator and the operating system (OS). Checking both of these are relatively easy to do.

To check the operating system, turn on your calculator and press 2nd, MEM (located on the + key) There will be a menu titled "MEMORY"  that pops up. Choose ABOUT. There will be a screen that shows themodel of calculator, current operating system, product # and ID and a website for help with your calculator. The operating system I have is 2.55. You can download it HERE at education.ti.com. Click on "TI-84 Plus family Operating System" and if propmted to log-in click "Continue As Guest" A download window should pop up and you can save the file to your computer.

If your operating system is not 2.55 you can try to continue with the instructable but I make no gaurantees that the program will work or that all of the commands will be available to you. Should you choose to download the new OS then you will need the Possibly Required Materials listed above. To transfer your new OS to your calculator you will need TI Connect.

TI Connect is a program that can be used to backup and restore items on your calculator should your ever data be erased. The download is available HERE.

In my pictures I took screen shots of each label individually. You don't have to leave alot of lines between blocks of code, however I usually leave one blank line.

## Step 2: Tips & Hints

Here are some tips and hints to help you along your way while programming. To exit the program you can press 2nd QUIT (located on the MODE key). Doing this will also save your program.

Some common keys that you will use while programming can be hard to find if you don't know where to look. If I can't find something use 2nd CATALOG (located on the 0 key) to view every option the calculator has. You can scroll through the list term by term or use the letters on the buttons to scroll to the first item starting with that particular letter.  For example when looking in the catalog pressing the E (SIN key) will take you to the section of the list beginning with the letter "E"

Listed in bold are some common keys that you will be using frequently.  Listed behind them are the key combinations used to find them.

ClrHome: PRGM (scroll to the I/O column) scroll down to option 8
Disp: PRGM
(scroll to the I/O column) option 3
Input: PRGM
(scroll to the I/O column) option 1
If: PRGM
(stay in the CTL column) option 1
Goto: PRGM
(stay in the CTL column) option 0 (after option 9)
Lbl: PRGM (stay in the CTL column) option 9
fPart(: MATH
(scroll to the NUM column) option 4
Stop: PRGM
(stay in the CTL column) scroll down to option F
Output(: PRGM
(scroll to the I/O column) option 6
Pause: PRGM
(stay in the CTL column) option 8

The = ≠ > ≥ < ≤ symbols are all located in the TEST menu. 2nd TEST (located on the MATH key)

## Step 3: Main Code

Here are the beginning lines of the program. This decides how to further dissect the equation.

## Step 4: Labels I, J, K, and L

This block of code further decides where to send the numbers to display the answers properly.

## Step 5: Label M

This is where the numbers go to be properly displayed for answers with a double real root.

## Step 6: Label N (Real Roots)

This is where numbers come to turn into properly displayed real roots.

## Step 7: Label O (Real Roots)

Numbers also can come here to be turned into real roots.

## Step 8: Label P (Real Roots)

More real roots! Almost done with these.

## Step 9: Label Q (Real Roots)

Only 3 more real root blocks.

## Step 10: Label R (Real Roots)

Almost close to being done.

## Step 11: Label S (Real Roots)

Last code block for real roots. Hooray!

## Step 12: Label T (Pure Imaginary)

These roots are strictly imaginary. They don't exist.

## Step 13: Label U (Pure Imaginary)

The numbers that go here are also imaginary.

## Step 14: Label V (Complex Roots)

Complex is the kind of numbers that come here to be displayed.

## Step 15: Label W (Complex Roots)

These roots are complex and imaginary. (Note the i in the display in picture 2)

## Step 16: Label X (Complex Roots)

The roots displayed here are also imaginary and complex.

## Step 17: Label Y (Complex Roots)

Last block of code that displays roots.

## Step 18: Label Theta, (The End)

This is the last block of code. You made it to the end. The θ (theta) symbol is located on the 3 key. Press ALPHA, 3 to get theta to pop up.

## Step 19: The End

After all of that programming your fingers will probably be tired. When they heal up, test out the program.

Are those images flipped?