Question

A) Se log3 81=x e log5 y=3, então x+y vale?

B) Se o log de 8/27 na base a é igual a 3 então o valor de a é?

Answer 1

A)

$log_3\;81=x\\\\81=3^x\\\\3^4=3^x\\\\x=4\\\\\\log_5\;y=3\\\\y=5^3\\\\y=125$

x + y = 4 + 125 = 129

B)

$log_a\;\frac{8}{27}=3\\\\\frac{8}{27}=a^3\\\\\left(\frac{2^3}{3^3}\right)=a^3\\ \\\left(\frac{2}{3}\right)^3=a^3\\\\a=\frac{2}{3}$