Symmetric Matrix
1. **Stating the problem:**
Determine if the matrix
$$\begin{bmatrix}1 & 5 \\ 5 & 1\end{bmatrix}$$
is symmetric.
2. **Definition of symmetric matrix:**
A matrix is symmetric if it is equal to its transpose, that is,
$$A = A^T$$
3. **Find the transpose of the matrix:**
The transpose is obtained by swapping rows and columns:
$$A^T = \begin{bmatrix}1 & 5 \\ 5 & 1\end{bmatrix}$$
4. **Compare the original matrix and its transpose:**
Here,
$$A = \begin{bmatrix}1 & 5 \\ 5 & 1\end{bmatrix}, \quad A^T = \begin{bmatrix}1 & 5 \\ 5 & 1\end{bmatrix}$$
Since the matrix equals its transpose,
$$A = A^T$$
5. **Conclusion:**
Matrix 14 is symmetric.
Final answer:
Matrix $$\begin{bmatrix}1 & 5 \\ 5 & 1\end{bmatrix}$$ is symmetric.