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D( x )
x = 0
(1/3)*x^-2 <= 0
x = 0
x = 0
(1/3)*x^-2 <= 0
(1/3)*x^-2 <= 0
1/3*x^-2 <= 0
1/3*x^-2 <= 0 // : 1/3
x^-2 <= 0/1/3
x^-2 <= 0
1/(x^2) <= 0
x <> 0
1/(x^2) <= 0 // * x^4
(x^4)/(x^2) <= 0
x^2 <= 0
x belongs to the empty set
x in (-oo:0) U (0:+oo)
ln((1/3)*x^-2) = 0
ln((1/3)*x^-2) = ln(e^0)
(1/3)*x^-2 = e^0
(1/3)*x^-2-e^0 = 0
1/3*x^-2 = 1 // : 1/3
x^-2 = 3
-2 < 0
1/(x^2) = 3 // * x^2
1 = 3*x^2 // : 3
1/3 = x^2
x^2 = 1/3 // ^ 1/2
abs(x) = (1/3)^(1/2)
x = (1/3)^(1/2) or x = -(1/3)^(1/2)
x in { (1/3)^(1/2), -(1/3)^(1/2) }
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