We need to find a if 729^a - 57 = 0
729^a - 57 = 0
=> 729^a = 57
As the base cannot be equated we can use logarithms
log (729^a) = log 57
use the property log a^b = b*log a
=> a*log 729 = log 57
=> a = log 57 / log 729
The value of a = log 57/log 729