Find the product of the following two matrices

3 -2| 1 -1
0 1| 1 1

1 answer

To find the product of two matrices, we follow the matrix multiplication rules. Let’s denote the matrices as follows:

Matrix A: \[ A = \begin{pmatrix} 3 & -2 \ 0 & 1 \end{pmatrix} \]

Matrix B: \[ B = \begin{pmatrix} 1 & -1 \ 1 & 1 \end{pmatrix} \]

The product \(C = AB\) is calculated using the formula for matrix multiplication:

\[ C_{ij} = \sum_{k} A_{ik} B_{kj} \]

Now, we will multiply matrix A by matrix B:

  1. Calculate \(C_{11}\): \[ C_{11} = A_{11}B_{11} + A_{12}B_{21} = 3 \cdot 1 + (-2) \cdot 1 = 3 - 2 = 1 \]

  2. Calculate \(C_{12}\): \[ C_{12} = A_{11}B_{12} + A_{12}B_{22} = 3 \cdot (-1) + (-2) \cdot 1 = -3 - 2 = -5 \]

  3. Calculate \(C_{21}\): \[ C_{21} = A_{21}B_{11} + A_{22}B_{21} = 0 \cdot 1 + 1 \cdot 1 = 0 + 1 = 1 \]

  4. Calculate \(C_{22}\): \[ C_{22} = A_{21}B_{12} + A_{22}B_{22} = 0 \cdot (-1) + 1 \cdot 1 = 0 + 1 = 1 \]

Putting it all together, we have: \[ C = \begin{pmatrix} C_{11} & C_{12} \ C_{21} & C_{22} \end{pmatrix} = \begin{pmatrix} 1 & -5 \ 1 & 1 \end{pmatrix} \]

Thus, the product of the two matrices is: \[ \begin{pmatrix} 1 & -5 \ 1 & 1 \end{pmatrix} \]