Question

resolva a equação a) x²-90=31 com calculo pff

Answer 1

$x^{2} -90=31\to \\\\ x^{2} =31+90\to \\\\ x^{2} =121\to \\\\ x=\pm \sqrt{121} \to \\\\ x=\pm 11\\\\\\ \boxed{S=\{-11;11\}}$

Answer 2

x² = 31 + 90
x² = 121
x = raiz de 121

x = 11