Question

x^2 - 4x - 16 = 0

Answer 1

\[x^2-4x=16\]
\[(x-2)^2=16+2^2=20\]
\[x-2=\pm\sqrt{20}=2\sqrt{5}\]
\[x=2\pm2\sqrt{5}\]

Answer 2

He's fast.

Answer 3

what does this sign mean? \[\pm\]