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D( x )
x = 0
x = 0
x = 0
x in (-oo:0) U (0:+oo)
4*x+7/x+1 = x+3 // - x+3
4*x-x+7/x-3+1 = 0
3*x^1+7*x^-1-2*x^0 = 0
(3*x^2-2*x^1+7*x^0)/(x^1) = 0 // * x^2
x^1*(3*x^2-2*x^1+7*x^0) = 0
x^1
3*x^2-2*x+7 = 0
3*x^2-2*x+7 = 0
DELTA = (-2)^2-(3*4*7)
DELTA = -80
DELTA < 0
x in { }
x belongs to the empty set
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