Let K = 0, 2, -3; -2, 0, 5; 3, -5, 0.. Find the entry of K² in row 1, column 1 and the sum of the…

Step 1. The first entry. Row $1$ is $(0, 2, -3)$ and column $1$ is $(0, -2, 3)$. The entry is $0 - 4 - 9 = -13$.

Step 2. The other diagonal entries. In the same way, row $2$ with column $2$ gives $-4 - 25 = -29$, and row $3$ with column $3$ gives $-9 - 25 = -34$.

Step 3. The sum. $-13 - 29 - 34 = -76$.

Step 4. The type. $(K^2)^T = (K^T)^2 = (-K)^2 = K^2$, so $K^2$ is symmetric.