If $A$ and $B$ are matrices of the same order, then $AB^T - BA^T$ is a

The system of equations

$x + y + z = 4$

$x + 2y + 3z = 12$

$x + 3y + \lambda z = \mu$ has a unique solution if

If $P = \begin{bmatrix}0 & 1\\ 1 & 1\end{bmatrix}$ and $Q = \begin{bmatrix}0 & -1\\ 1 & 0\end{bmatrix}$, then which of the following are correct?

(A) $P+Q$ is a singular matrix.

(B) $P-Q$ is a symmetric matrix.

(C) $P$ and $Q$ are non-singular matrices.

(D) $(P+Q)(P-Q) \neq P^2 - Q^2$

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Let $AX = B$ be a system of three linear equations in three variables. Then the system has

(A) a unique solutions if $|A| = 0$

(B) a unique solutions if $|A| \neq 0$

(C) no solutions if $|A| = 0$ and (adj A) $B \neq 0$

(D) infinitely many solutions if $|A| = 0$ and (adj A)$B = 0$

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If a, b and c are all different from zero and $\begin{vmatrix} 1+a & 1 & 1 \\ 1 & 1+b & 1 \\ 1 & 1 & 1+c \end{vmatrix} = 0$, then the value of $\frac{1}{a} + \frac{1}{b} + \frac{1}{c}$ is :

Assume $P$, $Q$, $R$ and $S$ are matrices of order $2 \times m$, $k \times n$, $m \times 2$ and $2 \times 3$ respectively. The restrictions on $k$, $m$ and $n$, so that $PQ + RS$ is defined are

If $A = \begin{bmatrix} 2 & -1 & 0 \\ 1 & 1 & 2 \\ -1 & 0 & 1 \end{bmatrix}$, then which of the following statement(s) is/are correct?

(A) A is singular matrix

(B) |3A| = 135

(C) |adj A| = 125

(D) $|A^{-1}| = \frac{1}{5}$

Choose the correct answer from the options given below: