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In x + In(x-1)=1

 Nov 28, 2016
 #1
avatar+118654 
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In x + In(x-1)=1

x>0

x-1>0      x>1

 

\(ln[x(x-1)]=1\\ ln[x^2-x]=1\\ e^{ln[x^2-x]}=e^1\\ x^2-x=e\\ x^2-x-e=0\\ x=\frac{1\pm\sqrt{1+4e}}{2}\\ \text{but x>1 so}\\ x=\frac{1+\sqrt{1+4e}}{2}\\\)
 

 Nov 28, 2016
 #2
avatar+118654 
0

check

 

LHS

=ln ((1+sqrt(1+4e))/2) + ln(((1+sqrt(1+4e))/2)-1)

= 0.9999999999999998  

=RHS

Melody  Nov 28, 2016

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