Fill in the missing number in the matrix:

[tex]\[
\begin{array}{cccc}
2 & -3 & 9 & 5 \\
8 & ? & 3 & 7 \\
-4 & 2 & 4 & -6 \\
5 & 2 & 8 & 1
\end{array}
\][/tex]



Answer :

Let's analyze the given matrix and the task at hand. The given matrix is:
[tex]\[ \begin{array}{cccc} 2 & -3 & 9 & 5 \\ 8 & ? & 3 & 7 \\ -4 & 2 & 4 & -6 \\ 5 & 2 & 8 & 1 \end{array} \][/tex]

The question involves finding the missing value, denoted by "?", in the second row of the matrix. To do this, let's follow a step-by-step approach.

1. Identify the row containing the missing value:
[tex]\[ 8, \; ?, \; 3, \; 7 \][/tex]

2. Calculate the sum of the known elements in the row:
[tex]\[ 8 + 3 + 7 = 18 \][/tex]

3. Count the number of known elements in the row:
[tex]\[ 3 \; (\text{elements: } 8, \; 3, \; 7) \][/tex]

4. Determine the average of the known elements in the row:
[tex]\[ \text{Average} = \frac{\text{Sum of known elements}}{\text{Number of known elements}} = \frac{18}{3} = 6 \][/tex]

5. The calculated average of the known elements is 6. Therefore, the missing value is 6. Update the matrix with the missing value:
[tex]\[ \begin{array}{cccc} 2 & -3 & 9 & 5 \\ 8 & 6 & 3 & 7 \\ -4 & 2 & 4 & -6 \\ 5 & 2 & 8 & 1 \end{array} \][/tex]

In conclusion, the missing value in the matrix is 6, and the updated matrix is:
[tex]\[ \begin{array}{cccc} 2 & -3 & 9 & 5 \\ 8 & 6 & 3 & 7 \\ -4 & 2 & 4 & -6 \\ 5 & 2 & 8 & 1 \end{array} \][/tex]

Intermediate results:
- Sum of known elements in the second row: 18
- Number of known elements: 3
- Calculated missing value: 6