Question

If \[\begin{bmatrix}1 & 0 & 0 \\ 0 & - 1 & 0 \\ 0 & 0 & - 1\end{bmatrix}\begin{bmatrix}x \\ y \\ z\end{bmatrix} = \begin{bmatrix}1 \\ 0 \\ 1\end{bmatrix}\], find x, y and z.

Answer 1

Here,
\[\begin{bmatrix}1 & 0 & 0 \\ 0 & - 1 & 0 \\ 0 & 0 & - 1\end{bmatrix}\begin{bmatrix}x \\ y \\ z\end{bmatrix} = \begin{bmatrix}1 \\ 0 \\ 1\end{bmatrix} \]
\[ \Rightarrow \begin{bmatrix}x \\ - y \\ - z\end{bmatrix} = \begin{bmatrix}1 \\ 0 \\ 1\end{bmatrix}\]
\[ \therefore x = 1, y = 0\text{ and }z = - 1\]