Question

Qual é o resultado de
x² + 49 = 0
() -6 e 6
() -7 e 7
() -8 e 8
() -9 e 9​

Answer 1

$x^2+49=0\\\\x^2+49-49=0-49\\\\\mathrm{Simplificar}\\\\x^2=-49\\\\x=\sqrt{-49},\:x=-\sqrt{-49}\\\\\sqrt{-49}=\sqrt{-1}\sqrt{49}\\\\=\sqrt{49}i\\\\=7i\\\\--\\\\-\sqrt{-49}\\\\\sqrt{-49}=\sqrt{-1}\sqrt{49}\\\\=\sqrt{49}i\\\\=-7i\\\\x=7i,\:x=-7i$

Se reparar temos a segunda opção.

( X ) -7 e 7