## Introduction: Quadratic Formula for the TI-83 and 84

Have you ever wondered if there is a way to make your calculator solve quadratic equations for you? Well, there is a fairly easy way to make your calculator do all the work for you.

Another program that I have put on Instructables is Heron's Formula.

www.instructables.com/id/Herons-Formula-program-for-the-TI-83-and-84/

## Step 1: Getting Started

You should know that a quadratic equation looks something like this: x^2-3x+2=0 or **ax^2+bx+c=0. **This will be important later on.

The first step is to press the program button on your calculator. Press the *right arrow *twice to get to new and select create new. Enter a name.

Now press *program* again and press the *right arrow* then press 2. To get letters, push the *alhpa* button. Now enter *A,B,C *and hit enter.

## Step 2: The Equation

Look at the first picture and put that on your calculator. Make sure you use the *negative* button before the first b! The -> is the store button. Press *sto-> *to get that. This just makes the equation equal to x. You may have noticed that this is only plus the square root of b squared... There is no button on this calculator for plus or minus so you will have to enter it as two separate equations.

Refer to the second picture for the second part of the equation. It is just like the first part except for a couple things.

## Step 3: Displaying Results

Press *program*, then the *right arrow*, then *3*. This will make the calculator display the answers. First open quotes (*alpha*, *+*) then put in 12 spaces (space is *alpha* then *0*) *x=* and close quotes. The equal sign is found by pressing *2nd* and then *math (test). *Then enter *,x,y* . (Hint: Press *2nd* then *alpha* to make it easier to type letters.) You can look at the picture if you need help. Make sure that you have the exact same thing as the picture below.

## Step 4: Using the Program

To exit out of this **do not hit clear!!! **This will delete everything on the line! Make sure you hit *2nd* then *mode (quit).*

Now push *program* and select the one you just made. Hit *enter* and type in the value of A. Then do this for B and C. Remember ax^2+bx+c=0. Example: x^2-3x+2=0; A=**1**, B=**-3** (use negative sign if necessary), C=**2. **The bold numbers are the numbers that you would enter in your program. After you enter all three variables hit *enter* and you get your answer.

## 74 Comments

Question 2 years ago on Step 3

My calculator just shows 3 dots instead of the answer. WTF IS WRONG!!

Question 3 years ago

Hi, I was able to do it from another tutorial similar to yours! My answers display in decimal forms (ex. 5.13467...). How do I make it display the answers as a square root (ex. 5√3)?

5 years ago

Mine says Err:NONREAL ANS anyone got any idea of what I can do to fix is?

Reply 3 years ago

Change the mode from “Real” to either “a + bi” or “re^0i” by pressing the Mode button

Reply 4 years ago

The program on step 2 above has an error. The equation should have parentheses around the 2A. It's written correctly in step 3.

Also, if your values of A, B, and C cause a negative under the square root, you will get a nonreal answer.

Reply 5 years ago

This means that the roots of the equation are complex, represented with i. You will learn more about complex numbers in algebra II. For now, the answer to the question "how many roots does this function have" should be no real solutions.

Question 4 years ago

How do you get the = sign on your calculator? I can't find the option anywhere.

Answer 3 years ago

“2nd” key + “MATH” key

Answer 3 years ago

click 2nd then math button under alpha

Question 4 years ago

I've triple checked my programs and even added parentheses as suggested in comments but keep betting 2.618... & .3819.... as answers. Is there some other setting that is incorrect on this calculator that could be giving me incorrect computations?

Answer 3 years ago

I'm also getting incorrect answers. This doesnt always give the correct answer Its telling me that 4.9t^2-6.86t+1.05 ends up being 4.2, 29.4.

4 years ago

I owe you my life and children

Reply 3 years ago

and possibly your wife as well

3 years ago

Many thanks for the effort you put in this!!!

4 years ago

These instructions are so easy to follow and helpful! Thank you!

4 years ago

Thank you so much!!

6 years ago

I have a TI-84, followed the instructions, and added parenthesis' around the variables to ensure I got correct answers with more complicated numbers. Works great, thanks!

Reply 4 years ago

If god is really you would be him

Question 4 years ago on Introduction

I cannot find the = sign onmy TI 84+Silver. Thanks Steve

5 years ago

U are the best!!!