Question

se 5^3a=64. o valor de 5^-a e?

Answer 1

Se

$5^3a = 64$

Então

$3a = log(base5) de 64$
$a = \frac {log(base5) 64}{3} = log (base5) 64^ \frac{1}{3} = log (base5) 4$



Assim

[tex] 5^(-a) = 5^(- log (base5) 4) = log (base5) 4^(-1) [\tex]
[tex] 5^(-a) = 4^(-1) = \frac {1}{4} [\tex]

Answer 2

$5^{3a} = 64$
$(5^{a})^{3} = 64$
$\sqrt[3]{ (5^{a})^{3}} = \sqrt[3]{64}$
$5^{a} = 4$
$5^{-a} = 1/4$