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D( x )
x = 0
x = 0
x = 0
x in (-oo:0) U (0:+oo)
100-(4*(0.01/x)) = 0.83 // - 0.83
100-(4*(0.01/x))-0.83 = 0
100-0.04*x^-1-0.83 = 0
-0.04*x^-1 = -99.17 // : -0.04
x^-1 = 2479.25
-1 < 0
1/(x^1) = 2479.25 // * x^1
1 = 2479.25*x^1 // : 2479.25
0.00040335 = x^1
x = 0.00040335
x = 0.00040335
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