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D( x )
x = 0
x = 0
x = 0
x in (-oo:0) U (0:+oo)
4/x = 0.66 // - 0.66
4/x-0.66 = 0
4*x^-1 = 0.66 // : 4
x^-1 = 0.165
-1 < 0
1/(x^1) = 0.165 // * x^1
1 = 0.165*x^1 // : 0.165
6.06060606 = x^1
x = 6.06060606
x = 6.06060606
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