TI-84 Plus CE field manual for IB Math
Solving 3×3 equations
Solve a linear system with a unique solution using the calculator's dedicated solver (TI-84 PlySmlt2, Nspire linSolve, Casio EQUA).
Solve the system x+z=5, 2x−y+3z=12, and −x+4y+z=5.
Press , choose PlySmlt2, and press any key if the app's about screen appears. On the app's menu, choose 2: Simultaneous Eqn Solver. On the SIMULT EQN SOLVER MODE screen, use / and / to move the cursor onto 3 for EQUATIONS and press to select it, then do the same to set UNKNOWNS to 3.
Press (the soft key under NEXT) to move to the equation entry screen. After each value you press for, the calculator prompts you to choose the sign of the next term. You could press there for a negative term, but it's simpler to just always press and fold the sign into the coefficient itself with . You already have to do that for the very first coefficient in a row anyway, since there's no sign prompt before it. Type each coefficient (using where the coefficient is negative), pressing after every value including the final constant. The missing y term in the first equation is a 0.
- Row 1:
1, 0, 1, 5 - Row 2:
2, -1, 3, 12 - Row 3:
-1, 4, 1, 5
Press (the soft key under SOLVE). The TI-84 solves the system and lists the unknowns.
x=2, y=1, and z=3.
Your turn
Work each one on your calculator, then check the answer.
- 1
Solve the system 2x+z=8, x−y+2z=8, 3x+2y−z=5.
- 2
Solve the system x+y+2z=4, 3y−z=11, 2x−y+z=−7.
- 3
Solve the system 4x−y+z=0, x+3z=−5, 2x+y−z=6.