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D( x )
ln(5/x) = 0
x = 0
5*x <= 0
5/x <= 0
ln(5/x) = 0
ln(5/x) = 0
ln(5/x) = ln(e^0)
5/x = e^0
5/x-e^0 = 0
5*x^-1 = 1 // : 5
x^-1 = 1/5
-1 < 0
1/(x^1) = 1/5 // * x^1
1 = 1/5*x^1 // : 1/5
5 = x^1
x = 5
x = 0
x = 0
5*x <= 0
5*x <= 0
5*x+0 <= 0 // - 0
5*x <= 0 // : 5
x <= 0/5
x <= 0
5/x <= 0
5/x <= 0
5*x^-1 <= 0
5*x^-1 <= 0 // : 5
x^-1 <= 0/5
x^-1 <= 0
1/(x^1) <= 0
x <> 0
1/(x^1) <= 0 // * x^2
(x^2)/(x^1) <= 0
x^1 <= 0
x <= 0
x in (-oo:0)
x in (0:5) U (5:+oo)
ln(5*x)/ln(5/x) = 0
ln(5*x)/ln(5/x) = 0 // * ln(5/x)
ln(5*x) = 0
ln(5*x) = ln(e^0)
5*x = e^0
5*x-e^0 = 0
5*x-1 = 0 // + 1
5*x = 1 // : 5
x = 1/5
x = 1/5
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