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**