Concept 9

Interpret and use matrices for simple computations/models when presented.

Read matrices by row and column and perform the simple computations the ACT asks for.

Core Idea

Read a matrix as organized numbers with a job. For multiplication, each entry comes from a row-by-column product, so position matters.

Understanding

Rule: When matrices appear on the ACT, the task is usually simple computation or interpretation, not abstract theory.

Focus on what each row and column represents and whether the dimensions make sense. If you are multiplying, slow down long enough to match the correct row with the correct column. Most errors happen because students read the entries correctly but combine the wrong ones.

Question

Worked Example

If $𝐴 = [2103]$ , what is the entry in row 1, column 2 of $𝐴 2$ ?

Select an answer to see the explanation