SOLUTION: log↓2(x-4)+log↓2(x)=5

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Question 1106348: log↓2(x-4)+log↓2(x)=5
Found 2 solutions by Alan3354, greenestamps:
Answer by Alan3354(69443)   (Show Source): You can put this solution on YOUR website!
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Answer by greenestamps(13203)   (Show Source): You can put this solution on YOUR website!


NOTE: you can write log base b of x as "log(b,x)". Or perhaps better, enclose the x in parentheses, as "log(b,(x))"


[rewrite the constant 5 as log base 2 of some number, so that all the terms in the equation are log base 2 of something]
[sum of logs = log of the product]
[algebra...]
[if the logs of the expressions are equal, the expressions are equal]


or

But x=-4 does not satisfy the original equation (log of a negative number is undefined).
x=8 satisfies the original equation, so the unique solution to the equation is x=8.

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