Question

Sendo 5^3a=64, o valor de 5^-a é?
a)-1/4
b)1/40
c)1/20
d)1/8
e)1/4

Answer 1

$\Large\boxed{\begin{array}{l}\sf5^{3a}=64\\\sf (5^a)^3=64\\\sf 5^a=\sqrt[\sf3]{\sf64}\\\sf 5^a=4\\\sf 5^{-a}=(5^a)^{-1}^=4^{-1}=\dfrac{1}{4}\\\huge\boxed{\boxed{\boxed{\boxed{\sf\maltese\,alternativa\,e}}}}\end{array}}$