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Solve for X

log 4x - log (2x-3) = log 6

 Jul 21, 2016
 #1
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Solve for X 
log 4x - log (2x-3) = log 6

 

\(log( 4x) - log (2x-3) = log 6\\ log(2* 2x) - log (2x-3) = log 6\\ log(2)+log(2x) - log (2x-3) = log3+log2\\ log(2x) - log (2x-3) = log(3)\\ log(\frac{2x}{2x-3})=log3\\ \frac{2x}{2x-3}=3\\ 2x=6x-9\\ -4x=-9\\ x=2\frac{1}{4}\)

 Jul 21, 2016
 #2
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There is a quicker way to do this. Since log( a/b ) = log a  - log b

then  log(4x) - log (2x-3) can be written as

log (4x)/(2x-3)

 

So log(4x)/(2x-3) =log 6

then

(4x)/(2x-3) =6    by equivalence

4x = 12x-18

8x=18

x=18/8=9/4

 Jul 21, 2016

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