This is LaTeX code:

[latex]
\det [A]_e^e = 0 \Rightarrow r([A]_e^e) = 3 \Rightarrow r(A) = 3 \Rightarrow \dim Im(A) = 3 \Rightarrow Im(A) = \mathbb{R}^3 \Rightarrow A
[/latex]