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.
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.