Question

X=2√3+-√20 isso tudo sobre 2

Answer 1

Olá.

$\mathsf{x=\dfrac{2\sqrt3\pm\sqrt{20}}{2}}\\\\\\ \mathsf{x=\dfrac{2\sqrt3\pm\sqrt{2^2\cdot5}}{2}}\\\\\\ \mathsf{x=\dfrac{2\sqrt3\pm2\sqrt{5}}{2}}\\\\\\ \mathsf{x=\dfrac{\diagup\!\!\!\!2(\sqrt3\pm\sqrt{5})}{\diagup\!\!\!\!2}}\\\\\\ \large\boxed{\mathsf{x=\sqrt3\pm\sqrt5}}$

Assumindo valores aproximados para essas raízes, teremos:
$\mathsf{x=1,73\pm2,24}\\\\ \mathsf{x'=1,73+2,24}\\ \boxed{\mathsf{x'=3,97}}\\\\ \mathsf{x''=1,73-2,24}\\ \boxed{\mathsf{x''=-0,51}}\\\\\\ \Large\boxed{\mathsf{S=\{x\in\mathbb{R}~|~x=0,51, 3,97~\}}}$

Qualquer dúvida, deixe nos comentários.
Bons estudos.