Question

quanto é 7-²: (7-³)² ?

Answer 1

Lembrete:

๏ $\mathsf{a^{-b}=\dfrac{1}{a^b}}$

๏ $\mathsf{\dfrac{a}{b}\div \dfrac{c}{d}=\dfrac{a}{b}\cdot \dfrac{d}{c}}$

๏ $\mathsf{\dfrac{a^n}{a^k}=a^{\left(n-k\right)}}$
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Resolução:

$\mathsf{\dfrac{7^{-2}}{\left(7^{-3}\right)^2}}\\\\\\\mathsf{\dfrac{\dfrac{1}{7^2}}{\left(7^{-6}\right)}}\\\\\\\mathsf{\dfrac{\dfrac{1}{7^2}}{\dfrac{1}{7^6}}}\\\\\\\mathsf{\dfrac{1}{7^2}\cdot \dfrac{7^6}{1}}\\\\\\\mathsf{\dfrac{7^6}{7^2}}\\\\\\\mathsf{7^{\left(6-2\right)}}\\\\\\\boxed{\mathsf{7^4\:ou\:2401}}\: \: \checkmark$

Answer 2

7-²:(7-³)² = 7⁴ ou 2401