Question

Calcule o valor de y em cada equação :
A) log4 y= 3
B) log9 y=1
C) logy 125=3

Answer 1

$a) \ \text{log}(4y) = 3 \Leftrightarrow 4y = 10^3 \\\\ 4y = 1000 \\ y = 25 \\\\ b) \ \text{log}(9y) = 1 \Leftrightarrow 9y = 10^1 \\\\ 9y = 10 \\ y = \frac{10}{9} \\\\ c) \ \text{log}(125y) = 3 \Leftrightarrow 125y = 10^3 \\\\ 125y = 1000 \\ y = 8 \\\\ d) \ \text{log}(\frac{1}{256}y) = -4 \Leftrightarrow \frac{1}{256}y = 10^{-4} \\\\ \frac{1}{256}y = \frac{1}{10000} \\\\ y = \frac{256}{10000} = \frac{16}{625}$