Question

como se resolve - 3x² + 85 = 0

Answer 1

Resposta:

$x = \pm\dfrac{\sqrt{255}}{3}$

Explicação passo-a-passo:

$- 3x^2 + 85 = 0\\\\\Rightarrow - 3x^2 = -85\\\\\Rightarrow x^2 = \dfrac{-85}{-3}\\\\\\\Rightarrow x^2 = \dfrac{85}{3}\\\\\\\Rightarrow x = \pm\sqrt{\dfrac{85}{3}}\\\\\\\Rightarrow x = \pm\dfrac{\sqrt{85}}{\sqrt{3}}\\\\\\\Rightarrow x = \pm\dfrac{\sqrt{85}}{\sqrt{3}}\times\dfrac{\sqrt{3}}{\sqrt{3}} \\\\\\\Rightarrow x = \pm\dfrac{\sqrt{85}\times\sqrt{3}}{\sqrt{3}^2}\\\\\\\Rightarrow x = \pm\dfrac{\sqrt{85\times3}}{3}\\\\\\\Rightarrow x = \pm\dfrac{\sqrt{255}}{3}$