Question

Se 3x-² = 1/27, então x é igual a,

Answer 1

Lembrete:

๏ $\mathsf{a^{-b}=\dfrac{1}{a^b}}$
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$\mathsf{3x^{-2}=\dfrac{1}{27}}\\\\\mathsf{3\cdot \dfrac{1}{x^2}=\dfrac{1}{27}}\\\\\mathsf{\dfrac{3}{x^2}=\dfrac{1}{27}}\\\\\mathsf{x^2=27\cdot 3}\\\mathsf{x^2=3\cdot 9\cdot 3}\\\mathsf{x^2=9\cdot 9}\\\mathsf{x^2=9^2}\\\mathsf{x=\pm\sqrt{9^2}}\\\mathsf{\boxed{\bold{x=\pm\:9}}}$

A solução sera:

$\boxed{\bold{\mathsf{S=\left\{x\in \mathbb{R}\:/\:x=\pm \:9\right\}}}}$