(1/3)^5х-1+(1/3)^5х=49

Решите задачу:

$( \frac{1}{3} ) ^{5x-1} +( \frac{1}{3} ) ^{5x} =49$
$( \frac{1}{3} ) ^{5x}:( \frac{1}{3} ) ^{1} +( \frac{1}{3} ) ^{5x} =49$
$( \frac{1}{3} ) ^{5x}*(3+1)=49$
$( \frac{1}{3} ) ^{5x}*4=49$
$( \frac{1}{3} ) ^{5x} = \frac{49}{4}$
$log_{ \frac{1}{3} } ( \frac{1}{3} ) ^{5x} = log_{ \frac{1}{3} } \frac{49}{4}$
$5x* log_{ \frac{1}{3} } \frac{1}{3}= log_{ \frac{1}{3} } \frac{49}{4}$
$5x*1= log_{ \frac{1}{3} } \frac{49}{4}$
$x= (log_{ \frac{1}{3} } \frac{49}{4} ):5$