# Programming TI-83 calculator to Solve Quadratic Equation?

• Mar 11th 2008, 06:29 PM
confused20
Programming TI-83 calculator to Solve Quadratic Equation?
Does anyone know how to program the TI-83 calculator to solve for quadratic equations? Thank you in advance for any input.
• Mar 12th 2008, 06:47 AM
earboth
Quote:

Originally Posted by confused20
Does anyone know how to program the TI-83 calculator to solve for quadratic equations? Thank you in advance for any input.

There are 2 different ways to use a TI83:
1. Use build-in Solver. I've attached a sequence of screenshots which show you how to use this program.

The "solve"-command is ALPHA+ENTER.

When you have typed the RHS of the equation the TI83 asks for a guess. I've typed -8 and then the TI83 calculates the negative solution of the equation. Afterwards I guessed 5 and the positive solution is calculated.

2. Write a program. I'll send you a listing in the next post.
• Mar 12th 2008, 06:55 AM
earboth
Quote:

Originally Posted by confused20
Does anyone know how to program the TI-83 calculator to solve for quadratic equations? Thank you in advance for any input.

Here comes the listing:

:ClrHome
:Input "A:",A
:Input "B:",B
:Input "C:",C
: Bē-4*A*C → D (remark the → is the STO> button)
:If D<0
:Then
:Disp "NO REAL SOLUTION"
:Else
:If D=0
:Then
:Disp "X=",-B/(2*A) (remark you have to use the sign minus, not the operation minus!)
:Else
:Disp "X=",-B/(2*A)-√(D)/(2*A)
:Disp "OR"
:Disp "X=",-B/(2*A)+√(D)/(2*A)
:End
:End

You find all commands either in the catalog (that's the easiest method to find them) or some of them in MATH or TEST.

The screenshot shows how this program works. You don't get imaginary or complex solutions!

As you may have noticed: I didn't smile all the time writing a program but I can't write double-point D without getting a grinning face.
• Mar 13th 2008, 04:53 AM
mr fantastic
Lovely replies, earboth (Clapping)
• Mar 13th 2008, 05:14 AM
earboth
Quote:

Originally Posted by confused20
Does anyone know how to program the TI-83 calculator to solve for quadratic equations? Thank you in advance for any input.

I've modified my program so you can calculate imaginary or complex solutions too.
The quadratic equation must be in the form

\$\displaystyle Ax^2+Bx+C=0\$

The \$\displaystyle \imath\$ is the first letter in the catalog if you come to the i-section.

Executing the program you only have to enter the coefficients A, B and C.
Code:

```PROGRAM:QUADSOLV :ClrHome :Input  "A:",A :Input  "B:",B :Input  "C:",C : Bē-4*A*C → D :If D<0 :Then :Disp "X=",-B/(2*A)+i*√(abs(D))/(2*A)  :Disp  "OR:" ::Disp "X=",-B/(2*A)-i*√(abs(D))/(2*A) :Else :If D=0 :Then :Disp  "X=",-B/(2*A) :Else :Disp "X=",-B/(2*A)-√(D)/(2*A) :Disp  "OR" :Disp "X=",-B/(2*A)+√(D)/(2*A) :End :End```