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How to solve simultaneous equations with a matrix on a TI-89 Titanium

By E-Code · updated

Type simult( (2nd ALPHA locks letters), the coefficient matrix, a comma and the column of right sides, then ENTER: for x+y=5 and x-y=1, simult([[1,1][1,-1]],[[5][1]]) gives [[3][2]], so x = 3 and y = 2.

Step by step

  1. Type simult(. 2nd ALPHA 3 9 5 + 4 T ALPHA ( Press 2nd ALPHA to lock letters, type s i m u l t (3 9 5 + 4 T), then ALPHA to unlock and (.
  2. Type the coefficients. 2nd , 2nd , 1 , 1 2nd ÷ 2nd , 1 , (-) 1 2nd ÷ 2nd ÷ , Type [[1,1][1,-1]], then a comma. 2nd , is [ and 2nd ÷ is ]; each [ ] is one equation's x and y numbers.
  3. Type the right sides. 2nd , 2nd , 5 2nd ÷ 2nd , 1 2nd ÷ 2nd ÷ ) Type [[5][1]] and ): the numbers after each =, one per row.
  4. Solve them. ENTER Press ENTER.
  5. Read the answer. The column [3, 2] means x = 3 and y = 2. Any number of equations works, as long as there is one row per equation.

What the screen shows

The column [3, 2] means x = 3 and y = 2. Any number of equations works, as long as there is one row per equation.

Look for [[3][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 simultaneous equations with a matrix” on the TI-89 calculator

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