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D( x )
x = 0
x = 0
x = 0
x in (-oo:0) U (0:+oo)
2.5/12 = 45.5/x // - 45.5/x
2.5/12-(45.5/x) = 0
2.5/12-45.5*x^-1 = 0
-45.5*x^-1 = -0.20833333 // : -45.5
x^-1 = 0.00457875
-1 < 0
1/(x^1) = 0.00457875 // * x^1
1 = 0.00457875*x^1 // : 0.00457875
218.4002184 = x^1
x = 218.4002184
x = 218.4002184
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