Question

calcule as raízes da equação de 5x 2-20=0

Answer 1

$5 x^{2} -20=0\to \\\\ 5 x^{2} =20\to \\\\ x^{2} = \frac{20}{5} \to \\\\ x^{2} =4\to \\\\ x=\pm \sqrt{4} \\\\ x=\pm 2\\\\\\\\ \boxed{S=\{-2;2\}}$