Question

log 1/4 din (7x+1)=log baza 9 din 27 dau 10 pct

Answer 1

$log_{ \frac{1}{4} } (7x+1) = log_9 27$, D = ($\frac{-1}{7}$; +∞)

$a = log_b (b^a) =\ \textgreater \ log_9 27 = log_ \frac{1}{4} ( (\frac{1}{4})^{log_9 27})$
$log_9 27 = \frac{3}{2}$
$\frac{1}{4}^{ \frac{3}{2}} = \frac{1}{ \sqrt[]{2^6} } = \frac{1}{8}$
$log_a f(x) = log_a g(x) =\ \textgreater \ f(x)=g(x)$

$7x+1 = \frac{1}{8} =\ \textgreater \ x = \frac{-1}{8}$ ∈ D