Step 1: Recall the property of skew-symmetric matrices
For a skew-symmetric matrix \( A \), \( A^T = -A \).
Step 2: Analyze \( AB + BA \)
Taking the transpose: \[ (AB + BA)^T = B^T A^T + A^T B^T = (-B)(-A) + (-A)(-B) = AB + BA. \] Thus, \( AB + BA \) is symmetric, as its transpose equals itself.
An amount of ₹ 10,000 is put into three investments at the rate of 10%, 12% and 15% per annum. The combined annual income of all three investments is ₹ 1,310, however, the combined annual income of the first and second investments is ₹ 190 short of the income from the third. Use matrix method and find the investment amount in each at the beginning of the year.
If \[ A = \begin{bmatrix} 1 & 2 & 0 \\ -2 & -1 & -2 \\ 0 & -1 & 1 \end{bmatrix} \] then find \( A^{-1} \). Hence, solve the system of linear equations: \[ x - 2y = 10, \] \[ 2x - y - z = 8, \] \[ -2y + z = 7. \]