This is LaTeX code:
[latex]
(4 x^2 - 8)^2 = 0 \ \Leftrightarrow \ 4 x^2 - 8 = 0 \ \Leftrightarrow \ x^2 = 2 \ \Leftrightarrow \ x \in \{ -\sqrt{2}, \sqrt{2} \}
[/latex]