The matrix $B$ given in the image is:

$B = \begin{bmatrix} 6 & -3 & \frac{1}{2} \end{bmatrix}$

Matrix elements are typically denoted as $b_{ij}$, where $i$ represents the row number and $j$ represents the column number.

Here, $b_{11}$ refers to the element in the first row and the first column of the matrix $B$.

So, $b_{11} = 6$.

Would you like further details or explanations?

Here are five related questions you might find interesting:

1. What is the significance of the matrix element $b_{12}$ in this matrix?
2. How do you identify elements in larger matrices?
3. What does it mean if a matrix element is zero?
4. Can you calculate the determinant of a matrix with a single row?
5. How would you transpose this matrix?

Tip: When working with matrices, always keep track of the row and column indices to correctly identify specific elements.