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How to solve a system of equations on a TI-89 Titanium

By E-Code · updated

Press F2 1 for solve(, type the equations joined by and (2nd 5 for MATH, 8 Test, 7 and), then a comma and the letters in braces: solve(x+y=5 and x-y=1,{x,y}) gives x = 3 and y = 2.

Step by step

  1. Start solve(. F2 1 Press F2, then 1 for solve(.
  2. Type the first equation. X + Y = 5 Type x+y=5. X and Y have their own keys.
  3. Open MATH. 2nd 5 Press 2nd, then 5. MATH is written above 5.
  4. Open Test. 8 Press 8 for Test, the menu of comparisons and logic words.
  5. Pick and. 7 Press 7 for and. It joins the two equations: both must be true.
  6. Finish the line. X − Y = 1 , 2nd ( X , Y 2nd ) ) Type x-y=1, a comma, then {x,y} and ). 2nd ( and 2nd ) type the braces: they list the letters to solve for.
  7. Solve both at once. ENTER Press ENTER.
  8. Read the answer. x = 3 and y = 2 makes both equations true: 3+2 = 5 and 3-2 = 1. Add more equations with and, and more letters in the {}.

What the screen shows

x = 3 and y = 2 makes both equations true: 3+2 = 5 and 3-2 = 1. Add more equations with and, and more letters in the {}.

Look for x = 3 and y = 2 on the screen.

Try it with the keys lit up

This guide is one of E-Code's Learn lessons. Open it on E-Code's TI-89 calculator and each key lights up in turn as you press it.

Try “Solve a system of equations” on the TI-89 calculator

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