If the system of equations $x – ky – z = 0$, $kx – y – z = 0$ and $x + y – z = 0$ has a non zero solution, then the possible value of k are

The number of real values $\lambda$, such that the system of linear equations $2 x-3 y+5 z=9$  ;  $x+3 y-z=-18$    ; $3 x-y+\left(\lambda^{2}-1 \lambda \mid\right) z=16$ has no solution, is :-

Statement $1$ : If the system of equations $x + ky + 3z = 0, 3x+ ky – 2z = 0, 2x + 3y – 4z = 0$ has a nontrivial solution, then the value of $k$ is $\frac{31}{2}$

Statement $2$ : A system of three homogeneous equations in three variables has a non trivial solution if the determinant of the coefficient matrix is zero.

The number of solutions of the equations $x + 4y – z = 0,$ $3x – 4y – z = 0,\,x – 3y + z = 0$ is

If $A = \int\limits_1^{\sin \theta } {\frac{t}{{1 + {t^2}}}} dt$ and $B = \int\limits_1^{\cos ec\theta } {\frac{dt}{{t\left( {1 + {t^2}} \right)}}} $ , (where $\theta  \in \left( {0,\frac{\pi }{2}} \right))$, then the-value of $\left| {\begin{array}{*{20}{c}}
A&{{A^2}}&{ – B}\\
{{e^{A + B}}}&{{B^2}}&{ – 1}\\
1&{{A^2} + {B^2}}&{ – 1}
\end{array}} \right|$ is