SOLUTION: hello. i need help with these few problems. {{{ log ( 2, 25 ) }}} and {{{ log ( 2, 3/5 ) }}} and {{{ log ( 2, 15 ) }}} and {{{ log ( 2, 75 ) }}} i just dont know how to approach th

Algebra ->  Logarithm Solvers, Trainers and Word Problems -> SOLUTION: hello. i need help with these few problems. {{{ log ( 2, 25 ) }}} and {{{ log ( 2, 3/5 ) }}} and {{{ log ( 2, 15 ) }}} and {{{ log ( 2, 75 ) }}} i just dont know how to approach th      Log On


   



Question 439520: hello. i need help with these few problems. +log+%28+2%2C+25+%29+ and +log+%28+2%2C+3%2F5+%29+ and +log+%28+2%2C+15+%29+ and +log+%28+2%2C+75+%29+ i just dont know how to approach these. Thanks
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
log ( 2, 25 ) }}} and +log+%28+2%2C+3%2F5+%29+ and +log+%28+2%2C+15+%29+ and +log+%28+2%2C+75+%29+
-------------
There is a Law of Logs called the change of base law.
It says: loga(b) = logc(b)/logc(a)
where c is any base you care to use.
-----------------------------------------
Your problem:
log2(25) = log(25)/log(2) = 1.3979/0.3010 = 4.644
================
Using your calculator:
log2(3/5) = log(3/5)/log(2) = -0.7370
---
log2(75) = log(75)/log(2) = 6.2288
=======================================
Cheers,
Stan H.