SOLUTION: lnx+ln(x+8)=4 i need help on how to solve this step by step

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Question 928273: lnx+ln(x+8)=4
i need help on how to solve this step by step
Answer by KMST(5328) About Me  (Show Source):
You can put this solution on YOUR website!
ln%28x%29%2Bln%28x%2B8%29=4
ln%28x%28x%2B8%29%29=4
ln%28x%5E2%2B8x%29=4
That is a base e logarithm, so
x%5E2%2B8x=e%5E4<--->x%5E2%2B8x-e%5E4=0
That is a quadratic equation.
We cannot solve this one by factoring, because the result is not a rational number.
We can use the quadratic formula, as a computer would do,
but humans would solve it easier and with more understanding by completing the square:
x%5E2%2B8x=e%5E4
x%5E2%2B8x%2B16=e%5E4%2B16
%28x%2B4%29%5E2=e%5E4%2B16--->x%2B4=0+%2B-+sqrt%28e%5E4%2B16%29--->x=-4+%2B-+sqrt%28e%5E4%2B16%29