SOLUTION: Given that {{{u=log(9,x)}}}, find in terms of u, {{{log(2,81)}}} *PLEASE ANSWER AS SOON AS POSSIBLE BRO!!!!!! :) =)

Algebra ->  Logarithm Solvers, Trainers and Word Problems -> SOLUTION: Given that {{{u=log(9,x)}}}, find in terms of u, {{{log(2,81)}}} *PLEASE ANSWER AS SOON AS POSSIBLE BRO!!!!!! :) =)      Log On


   

Question 467006: Given that u=log%289%2Cx%29, find in terms of u,
log%282%2C81%29



*PLEASE ANSWER AS SOON AS POSSIBLE BRO!!!!!! :) =)
Answer by Edwin McCravy(20060) About Me  (Show Source):
You can put this solution on YOUR website!
u=log%289%2Cx%29
Erase the log and swap the two outer numbers,
leaving the base of the log as the base of
the exponent:

x=9%5Eu

----------------------

To find log%282%2C81%29 use the change of base formula:

log%28OLD_BASE%2CA%29=+log%28NEW_BASE%2CA%29%2Flog%28NEW_BASE%2COLD_BASE%29

We have logs base 10 on the calculator so we let the new base
be 10 and the old base be 2

log%282%2C81%29=log%2810%2C81%29%2Flog%2810%2C2%29=1.908485019%2F0.3010299957=6.339850003 

Edwin