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Jul 27th, 2006, 04:46 AM
#11
Addicted Member
Re: logarithmic equations
2. (2 - log 25)/(log square root of 8)
= ( 2 - 2 log 5 )/( 1/2 log 8 )
= 4 [1 - log5]/[log8]
Which you already had. I'm assuming you are doing logs base 10 which makes
1 = log 10
so now have 4[log 10 - log 5]/[log 8]
= [4 log 2]/[3 log 2] using log(a) - log(b) = log(a/b) and log(8) = 3 log(2)
= 4/3
Usually if you are using logs and no base is quoted you are woking with base 10 (unless ln is written in which case you are using base e). Since this gives us a very nice answer I have no reason to doubt that we are using base 10 in this case. My working would give the same answer as kberry79 if I had not assumed we are working in base 10 and therefore left 1 alone.
1/log (8) does not equal log (8)^-1 so that method was incorrect
1/log (8) = 1 - log (8) = 1 + log (8)^-1
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