grandes-ecoles 2010 QIIB

grandes-ecoles · France · centrale-maths2__pc Matrices Linear Transformation and Endomorphism Properties
Show that the application $$\begin{aligned} j : & \mathbb { K } ^ { 3 } \longrightarrow \mathcal { M } _ { 0 } ( 2 , \mathbb { K } ) \\ \left( \begin{array} { l } x \\ y \\ z \end{array} \right) & \longmapsto \left( \begin{array} { c c } x & y + z \\ y - z & - x \end{array} \right) \end{aligned}$$ is an isomorphism of $\mathbb { K }$-vector spaces.
Show that the application
$$\begin{aligned}
j : & \mathbb { K } ^ { 3 } \longrightarrow \mathcal { M } _ { 0 } ( 2 , \mathbb { K } ) \\
\left( \begin{array} { l } x \\ y \\ z \end{array} \right) & \longmapsto \left( \begin{array} { c c } x & y + z \\ y - z & - x \end{array} \right)
\end{aligned}$$
is an isomorphism of $\mathbb { K }$-vector spaces.