Question 1202165:  Determine the appropriate base of each logarithm 
log base b (1/15)=-1.9 
log base b 80=3.9 
log base b 6=0.9 
log base b 66=3.1 
 
 Answer by Alan3354(69443)      (Show Source): 
You can  put this solution on YOUR website! Determine the appropriate base of each logarithm 
log base b (1/15)=-1.9 
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---> b^-1.9 = 1/15 
Solve for b 
Using ln, natural logs, base e: 
-1.9*ln(b) = ln(1/15)  
ln(b) = ln(1/15)/(-1.9) 
ln(b) = -2.708/(-1.9) = ~1.4252 
b = e^(1.4252) 
b =~ 4.159 
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log base b 80=3.9 
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b^3.9 = 80 
Using common logs, base 10: 
3.9*log(b) = log(80) 
log(b) = log(80)/3.9 = ~0.48797 
b = 10^(0.48797) = ~3.0759 
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log base b 6=0.9 
log base b 66=3.1 
 
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