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D( x )
x = 0
x = 0
x = 0
x in (-oo:0) U (0:+oo)
100 = 1.3/x // - 1.3/x
100-(1.3/x) = 0
100-1.3*x^-1 = 0
-1.3*x^-1 = -100 // : -1.3
x^-1 = 76.92307692
-1 < 0
1/(x^1) = 76.92307692 // * x^1
1 = 76.92307692*x^1 // : 76.92307692
0.013 = x^1
x = 0.013
x = 0.013
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