Dawnbridge

TI-Nspire CX II field manual for IB Math

AI HL only · 37 of 45

37

Matrix arithmetic

AI HL

Store two matrices and evaluate a matrix expression such as A3B on the calculation screen.

Goal

Given ​A=[13​21​]​ and ​B=[21​03​], find ​A3B.

1

Store the first matrix: type a:= with , insert a 2 x 2 matrix template with → 7: Matrix & Vector → 1: Create → 1: Matrix — in the dialog, type to set the rows and columns ( moves between the fields; the arrows change the numbers instead). Fill the entries 1, 2, 3, 1 (move between cells with ), and press .

Scratchpad
RAD
a:=[13​21​]
[13​21​]
2

Store the second matrix the same way, but as b ( ).

Scratchpad
RAD
b:=[21​03​]
[21​03​]
3

Type , press on the touchpad to leave the exponent, then , and press .

Scratchpad
RAD
a3⋅b
[5673​5457​]
Result

​A3B=[5673​5457​].

Storing the matrices is optional — you can type both matrix templates straight into one expression, such as ​([13​21​])3⋅[21​03​], and evaluate it in one line. Named matrices earn their keystrokes when a question reuses ​A​ and ​B​ across several parts.

Your turn

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

  1. 1

    Given ​A=[21​11​]​ and ​B=[12​30​], find ​A3B.

  2. 2

    Given ​A=[12​−10​]​ and ​B=[30​12​], find ​A3B.

  3. 3

    Given ​A=[01​21​]​ and ​B=[23​10​], find ​A3B.