Resumen

\[x^2 = 64\]
\[x=\boxed{-8, 8}\]

\[x^2 = 16\]
\[x=\boxed{-4, 4}\]

\[x^2 + 1 = 5\]
\[x=\boxed{-2, 2}\]

\[4(x^2 + 1) = 20\]
\[x=\boxed{-2, 2}\]

\[2(x^2 + 1) = \frac{218}{9}\]
\[x=\boxed{\frac{-10}{3}, \frac{10}{3}}\]

\[( x + 4 ) ( x - 3 ) = 0\]
\[x=\boxed{-4, 3}\]