Question

find x if log k x.log5k = 3

Answer 1

Use log(A,B) = 1/log(B,A) 

log (k,x) * log(5,k) = 3 

log (k,x) / log(k,5) = 3 

log(k, x) = 3 log(k, 5) 

log(k, x) = log(k, 5^3) 

x = 5^3 = 125 

YOU COULD HAVE also used log(A,B) / log(A,C) = lob(C, B) 

log (k,x) / log(k,5) = 3 
log(5, x) = 3 
x = 5^3 = 125 

Now that I think of it 
YOU COULD HAVE also used log(A,B) × log(B,C) = lob(A, C) 
log (k,x) × log(5,k) = 3 
log(5,k) × log (k,x) = 3 
log(5, x) = 3 
x = 5^3 = 125