Problem
What are the dimensions of the matrix \( A = \left[ \begin{array}{ccc} 1 & 2 & 3 \\ 4 & 5 & 6 \\ 7 & 8 & 9 \end{array} \right] \)?
Solution
Step 1 ：A matrix's dimensions are given by the number of rows and the number of columns, respectively.
Step 2 ：Count the number of rows: In matrix A, there are 3 rows.
Step 3 ：Count the number of columns: In matrix A, there are 3 columns.
