Which of the following matrices is an identity matrix of order $3 \times 3$?
Question 2
If matrix $A = \begin{pmatrix} 2 & 3 \\ 1 & 4 \end{pmatrix}$ and matrix $B = \begin{pmatrix} -1 & 0 \\ 5 & -2 \end{pmatrix}$, what is $A - B$?
Question 3
What is the result of multiplying matrix $A = \begin{pmatrix} 1 & 2 \\ 3 & 4 \end{pmatrix}$ by the scalar $k = -2$?
Question 4
If matrix $P = \begin{pmatrix} 1 & 2 \end{pmatrix}$ and matrix $Q = \begin{pmatrix} 3 \\ 4 \end{pmatrix}$, what is the product $PQ$?
Question 5
A company tracks its sales of two products, Product X and Product Y, over two quarters. The sales for Quarter 1 are 100 units of Product X and 150 units of Product Y. For Quarter 2, sales are 120 units of Product X and 180 units of Product Y. Which matrix correctly represents the total sales data for each product over the two quarters?
