Question

Me ajudem por favor com essas questões: a) x²=9 b) 3x²=27 c) -2x² 7=0

Answer 1

$a)~x^2=9\to \\\\x=\pm \sqrt{9} \to\\\\ x=\pm~3\\\\\\ \boxed{\boxed{S=\{-3~;~3\}}}$




$b)~3x^2=27\to\\\\ x^2= \dfrac{27}{3} \to \\\\x^2=9\to \\\\x=\pm \sqrt{9} \to\\\\ x=\pm~3\\\\\\ \boxed{\boxed{S=\{-3~;~3\}}}$




$-2x^2+7=0\to \\\\ -2x^2=-7~~(-1)\to \\\\ 2x^2=7\to\\\\ x^2= \dfrac{7}{2} \to \\\\ x=\pm \sqrt{\dfrac{7}{2} } \\\\\\ \boxed{\boxed{S=\{-\sqrt{\dfrac{7}{2} } ~;~\sqrt{\dfrac{7}{2} } \}}}$