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2=lnx+2x                                    the answer is x=1 but i dont see who they got that

 Dec 19, 2016
edited by Guest  Dec 19, 2016
edited by Guest  Dec 19, 2016

Best Answer 

 #2
avatar+14985 
+5

2=lnx+2x the answer is x=1 but i dont see who they got that

 

\(2=lnx+2x\)

 

\(lnx=2(1-x)\)

 

\(\frac{lnx}{2}=1-x\)

 

\(ln\sqrt x=1-x\)

 

\(x+ln\sqrt x=1\)

 

\(f(x)=x+ln\sqrt x-1=0\)

 

\(\LARGE x=1\)

 

 

laugh  !

 Dec 20, 2016
 #1
avatar+118654 
+5

2=lnx+2x    

 

I think I would graph  y=lnx+2x-2   using a graphing calculator and see where y=0

 

There is no super straight forward algebraic way of doing it, although someone may come up with some complicated method.  One must exist. :)

 

You can see from the graph that x=1 is the only answer.

 

 

 Dec 20, 2016
 #2
avatar+14985 
+5
Best Answer

2=lnx+2x the answer is x=1 but i dont see who they got that

 

\(2=lnx+2x\)

 

\(lnx=2(1-x)\)

 

\(\frac{lnx}{2}=1-x\)

 

\(ln\sqrt x=1-x\)

 

\(x+ln\sqrt x=1\)

 

\(f(x)=x+ln\sqrt x-1=0\)

 

\(\LARGE x=1\)

 

 

laugh  !

asinus Dec 20, 2016
 #3
avatar
0

Rewrite the equation as

2 - 2x = ln(x),

and sketch the two graphs y = 2 - 2x and y = ln(x).

(You shouldn't need a graph plotter to do this).

Solutions to the equation will be the x co-ordinates of their points of intersection. Clearly there is just one, at x = 1.

 Dec 20, 2016

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