Sagot :
[tex]x^2+4x-4=0 \\
x^2+4x+4-4-4=0 \\
(x+2)^2-8=0 \\
(x+2)^2=8 \\
x+2=\pm \sqrt{8} \\
x+2=\pm \sqrt{4 \times 2} \\
x+2=\pm2\sqrt{2} \\
x+2=-2\sqrt{2} \ \lor \ x+2=2\sqrt{2} \\
x=-2\sqrt{2}-2 \ \lor \ x=2\sqrt{2}-2 \\
\boxed{x=-2\sqrt{2}-2 \hbox{ or } x=2\sqrt{2}-2}[/tex]
[tex]x^2+4x-4=0 \\
x^2+4x+4-8=0\\
(x+2)^2=8\\
x+2=-\sqrt8 \vee x+2=\sqrt8\\
x=-2-2\sqrt2 \vee x=-2+2\sqrt2[/tex]