Question

x ao quadrado menos 64 igual a zero

Answer 1

x² - 64 = 0 
x² = 64
x = \/64
x = +/- 8

Answer 2

$x^{2} -64=0\to \\\\ x^{2} =64\to \\\\x=\pm \sqrt{64} \to \\\\ x=\pm 8\\\\\\ S=\{-8;8\}$