\(x^2+4x-4=0 \\
x^2+4x+4-4-4=0 \\
(x+2)^2-8=0 \\
(x+2)^2=8 \\
x+2=\pm \sqrt{8} \\
x+2=\pm \sqrt{4 \times 2} \\
x+2=\pm2\sqrt{2} \\
x+2=-2\sqrt{2} \ \lor \ x+2=2\sqrt{2} \\
x=-2\sqrt{2}-2 \ \lor \ x=2\sqrt{2}-2 \\
\boxed{x=-2\sqrt{2}-2 \hbox{ or } x=2\sqrt{2}-2}\)
