If the roots of the equation $z^4 + z^3 + (-36 + 15i)z^2 + mz = 0$ are the vertices of a square then $(\lambda + m)$ can be equal to
Step-by-Step Solution
Key Concept: Subtract cases with common vertices or sides from total pairs to find disjoint selections.
Step 1: Determine the total number of $2 \times 2$ squares in the specified grid.
The problem statement indicates that there are $7 \times 7$ such squares.
$$ \text{Total number of } 2 \times 2 \text{ squares } (N) = 7 \times 7 = 49 $$
Step 2: Calculate the total number of ways to select two distinct squares from the available squares.
This is a combination problem, selecting 2 squares out of $N=49$ squares, denoted as $\binom{N}{2}$.
$$ \text{Total pairs of squares} = \binom{49}{2} = \frac{49 \times (49-1)}{2} = \frac{49 \times 48}{2} = 49 \times 24 = 1176 $$
Step 3: Identify the number of pairs of squares that share exactly one common vertex.
The provided solution states this number directly. We assume this count refers to pairs that share a vertex but not a side, to allow for direct subtraction.
$$ \text{Pairs sharing a common vertex (only)} = 7 \times 7 \times 2 = 98 $$
Step 4: Identify the number of pairs of squares that share at least one common side.
The provided solution states this number directly.
$$ \text{Pairs sharing a common side} = 7 \times 8 \times 2 = 112 $$
Step 5: Calculate the number of ways to select two squares that share neither a common vertex nor a common side.
To find this, we subtract the number of pairs sharing a vertex (only) and the number of pairs sharing a side from the total number of pairs.
$$ \text{Pairs sharing neither vertex nor side} = \text{Total pairs} - \text{Pairs sharing a vertex (only)} - \text{Pairs sharing a side} $$
$$ = 1176 - 98 - 112 $$
$$ = 1176 - (98 + 112) $$
$$ = 1176 - 210 $$
$$ = 966 $$
The final answer is $\boxed{966}$.
Correct Answer: 1,2