Dawnbridge

TI-Nspire CX II field manual for IB Math

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11

Solving 3×3 equations

All courses

Solve a linear system with a unique solution using the calculator's dedicated solver (TI-84 PlySmlt2, Nspire linSolve, Casio EQUA).

Goal

Solve the system ​x+z=5,  ​2x−y+3z=12, and ​−x+4y+z=5.

1

From the Scratchpad calculator, press → 3: Algebra → 2: Solve System of Linear Equations. In the dialog, type to set Number of equations: 3, press to reach the Variables field and type x,y,z with , then press .

Scratchpad
RAD
Solve a System of Linear Equations
Number of equations:3▶
Variables:x,y,z▶
Enter variable names separated by commas
OKCancel
2

OK pastes a linSolve template with three empty equation boxes onto the entry line. Type each equation exactly as written: no rearranging, and a missing term is simply left out. First box: , then to the next box.

3

Second box: , then . Third box: . Note the negative-sign key for the leading ​−x.

4

Press . The Nspire returns the solution as a list in variable order: ​{2,1,3}​ means ​x=2,  ​y=1,  ​z=3.

Scratchpad
RAD
linSolve⎝⎜⎛​⎩⎪⎨⎪⎧​x+z=52⋅x−y+3⋅z=12−x+4⋅y+z=5​,{x,y,z}⎠⎟⎞​
{2.,1.,3.}
Result

​x=2,  ​y=1, and ​z=3.

Your turn

Work each one on your calculator, then check the answer.

  1. 1

    Solve the system ​2x+z=8,  ​x−y+2z=8,  ​3x+2y−z=5.

  2. 2

    Solve the system ​x+y+2z=4,  ​3y−z=11,  ​2x−y+z=−7.

  3. 3

    Solve the system ​4x−y+z=0,  ​x+3z=−5,  ​2x+y−z=6.