If $A = \left[ {\begin{array}{*{20}{c}}\alpha &2\\2&\alpha \end{array}} \right]$ and $|{A^3}|$=125, then $\alpha = $

If $\omega $ be a complex cube root of unity, then $\left| {\,\begin{array}{*{20}{c}}1&\omega &{ – {\omega ^2}/2}\\1&1&1\\1&{ – 1}&0\end{array}\,} \right| = $

The system of linear equations $x + \lambda y – z = 0,\lambda x – y – z = 0\;,\;x + y – \lambda z = 0$ has a non-trivial solution for:

Show that points $A(a, b+c), B(b, c+a), C(c, a+b)$ are collinear

Find the equation of the line joining $\mathrm{A}(1,3)$ and $\mathrm{B}(0,0)$ using determinants and find $\mathrm{k}$ if $\mathrm{D}(\mathrm{k}, 0)$ is a point such that area of triangle $\mathrm{ABD}$ is $3 \,\mathrm{sq}$ $\mathrm{units}$.