lnx + ln(x-4) = ln5

Question

what is the answer to the question:

 

lnx =+ ln(x-4) = ln5

Answer 1

Arthur's answer is correct, as it copied the original problem correctly.  x=-1 is ruled out, because you can't take the log of a negative number, so only x=5 is a working solution.

Answer 2

ln(x)+ln(x-4)=ln(5)

ln[(x)(x-4)]=ln(5)

x(x-4)=5

x²-4x=5

x²-4x-5=0

(x-5)(x+1)=0

x-5=0

x=5

Answer 3

ln x  + ln(x+4) = ln5

 

ln(x(x+4)) = ln5

 

x(x+4) = 5

 

x² + 4x - 5 = 0

 

x² + 5x -x -5 =0

x(x+5) - (x+5) = 0

(x-1)(x+5) = 0

 

x=1 or x=-5

:)