I wish you wouldn't use that notation. I looked it up and
from what I read it means this. Let me know if it means
something else:
\log_6 (\frac{216^x}{1296^x})\log_x6
means this, I think:
Use the rule
Reduce the fraction, and use the rule
Move the exponent x out front:
Write as
Move the exponent -1 out front as a negative sign
Use the rule
Edwin