Eigenvalues Matrix E122A2
1. **State the problem:** Find the eigenvalues of the matrix $$\begin{bmatrix}4 & 1 \\ 2 & 3\end{bmatrix}$$.
2. **Formula:** Eigenvalues $\lambda$ satisfy the characteristic equation $$\det(A - \lambda I) = 0$$ where $A$ is the matrix and $I$ is the identity matrix.
3. **Set up the characteristic matrix:**
$$A - \lambda I = \begin{bmatrix}4 - \lambda & 1 \\ 2 & 3 - \lambda\end{bmatrix}$$
4. **Calculate the determinant:**
$$\det(A - \lambda I) = (4 - \lambda)(3 - \lambda) - (2)(1)$$
5. **Expand and simplify:**
$$= (4)(3) - 4\lambda - 3\lambda + \lambda^2 - 2 = 12 - 7\lambda + \lambda^2 - 2 = \lambda^2 - 7\lambda + 10$$
6. **Solve the quadratic equation:**
$$\lambda^2 - 7\lambda + 10 = 0$$
7. **Factor the quadratic:**
$$ (\lambda - 5)(\lambda - 2) = 0 $$
8. **Find eigenvalues:**
$$\lambda = 5 \quad \text{or} \quad \lambda = 2$$
**Final answer:** The eigenvalues of the matrix are $5$ and $2$.