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D( x )
x = 0
x = 0
x = 0
x in (-oo:0) U (0:+oo)
0.91 = 312/x // - 312/x
0.91-(312/x) = 0
0.91-312*x^-1 = 0
-312*x^-1 = -0.91 // : -312
x^-1 = 0.00291667
-1 < 0
1/(x^1) = 0.00291667 // * x^1
1 = 0.00291667*x^1 // : 0.00291667
342.85675102 = x^1
x = 342.85675102
x = 342.85675102
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