To find the missing number in the sequence, we need to determine a consistent algebraic pattern that applies to each row. Let's investigate the pattern row by row:

First row:
$6, -5, -6, 5$
We observe an alternating sign pattern, but we are looking for an algebraic relationship.

Second row:
$-4, 3, 2, -6$

Third row:
$6, 6, 9, 4$

Now, let's try to figure out an algebraic relationship that applies consistently across all rows using basic operations.

Investigating a Potential Equation

1. First column:

   • $6$, $-4$, $6$, $-9$

2. Second column:

   • $-5$, $3$, $6$, $?$

3. Third column:

   • $-6$, $2$, $9$, $6$

4. Fourth column:

   • $5$, $-6$, $4$, $3$

Trying Addition/Subtraction Patterns:

Look for a consistent difference:

• First and second column difference:
  $6 - (-5) = 11$
  $-4 - 3 = -7$
  $6 - 6 = 0$

• Third and fourth column difference:
  $-6 - 5 = -11$
  $2 - (-6) = 8$
  $9 - 4 = 5$

There seems to be no simple additive pattern.

Trying Multiplication Patterns:

Let's attempt a ratio approach.