1. **State the problem:** Find the adjoint (also called adjugate) of the matrices
$$A = \begin{bmatrix} 3 & 5 \\ 3 & 4 \end{bmatrix} \quad \text{and} \quad B = \begin{bmatrix} 2 & 3 \\ 1 & -2 \end{bmatrix}$$
2. **Recall the formula for the adjoint of a 2x2 matrix:**
For a matrix
$$M = \begin{bmatrix} a & b \\ c & d \end{bmatrix},$$
its adjoint is
$$\text{adj}(M) = \begin{bmatrix} d & -b \\ -c & a \end{bmatrix}.$$
This is the transpose of the cofactor matrix.
3. **Calculate the adjoint of matrix A:**
Given
$$A = \begin{bmatrix} 3 & 5 \\ 3 & 4 \end{bmatrix},$$
apply the formula:
$$\text{adj}(A) = \begin{bmatrix} 4 & -5 \\ -3 & 3 \end{bmatrix}.$$
4. **Calculate the adjoint of matrix B:**
Given
$$B = \begin{bmatrix} 2 & 3 \\ 1 & -2 \end{bmatrix},$$
apply the formula:
$$\text{adj}(B) = \begin{bmatrix} -2 & -3 \\ -1 & 2 \end{bmatrix}.$$
5. **Final answers:**
$$\boxed{\text{adj}(A) = \begin{bmatrix} 4 & -5 \\ -3 & 3 \end{bmatrix}, \quad \text{adj}(B) = \begin{bmatrix} -2 & -3 \\ -1 & 2 \end{bmatrix}}$$
Adjoint 2X2 F81A16
Step-by-step solutions with LaTeX - clean, fast, and student-friendly.