Evaluate the determinants
$\left|\begin{array}{ccc}0 & 1 & 2 \\ -1 & 0 & -3 \\ -2 & 3 & 0\end{array}\right|$
Let $A=\left[\begin{array}{ccc}0 & 1 & 2 \\ -1 & 0 & -3 \\ -2 & 3 & 0\end{array}\right]$
By expanding along the first row, we have:
$|A|=0\left|\begin{array}{ll}0 & -3 \\ 3 & 0\end{array}\right|-1\left|\begin{array}{ll}-1 & -3 \\ -2 & 0\end{array}\right|+2\left|\begin{array}{ll}-1 & 0 \\ -2 & 3\end{array}\right|$
$=0-1(0-6)+2(-3-0)$
$=-1(-6)+2(-3)$
$=6-6=0$
Let $\mathrm{A}(-1,1)$ and $\mathrm{B}(2,3)$ be two points and $\mathrm{P}$ be a variable point above the line $A B$ such that the area of $\triangle \mathrm{PAB}$ is $10$ . If the locus of $\mathrm{P}$ is $\mathrm{ax}+\mathrm{by}=15$, then $5 a+2 b$ is :
Let $P $ and $Q $ be $3×3$ matrices $P \ne Q$. If ${P^3} = {Q^3},{P^2}Q = {Q^2}P$ then determinant of $\det \left( {{P^2} + {Q^2}} \right)$ is equal to :
$\left| {\,\begin{array}{*{20}{c}}{{a_1}}&{m{a_1}}&{{b_1}}\\{{a_2}}&{m{a_2}}&{{b_2}}\\{{a_3}}&{m{a_3}}&{{b_3}}\end{array}\,} \right| = $
Statement $-1 :$Determinant of a skew-symmetric matrix of order $3$ is zero
Statement $-2 :$ For any matrix $A,$ $\det \left( {{A^T}} \right) = {\rm{det}}\left( A \right)$ and $\det \left( { - A} \right) = - {\rm{det}}\left( A \right)$ Where $\det \left( A \right) = A$. Then :
Let $\lambda, \mu \in R$. If the system of equations
$ 3 x+5 y+\lambda z=3 $
$ 7 x+11 y-9 z=2 $
$ 97 x+155 y-189 z=\mu$
has infinitely many solutions, then $\mu+2 \lambda$ is equal to :