We can drop the logarithm base-6 because both sides have the same thing. In order for the two logaritms to be equal, the inside parts of the logarithm must be equal. Logarithm is a one-to-one function.
However, this solution does not work. If we try to use r = 1/3 into
it yield
. There is no real solution because logarithm cannot be negative.
For your new question,