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D( x )
x = 0
x = 0
x = 0
x in (-oo:0) U (0:+oo)
1-(31.8/x) = 0.48 // - 0.48
1-(31.8/x)-0.48 = 0
1-31.8*x^-1-0.48 = 0
-31.8*x^-1 = -0.52 // : -31.8
x^-1 = 0.0163522
-1 < 0
1/(x^1) = 0.0163522 // * x^1
1 = 0.0163522*x^1 // : 0.0163522
61.15385086 = x^1
x = 61.15385086
x = 61.15385086
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