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D( x )
x = 0
x = 0
x = 0
x in (-oo:0) U (0:+oo)
12/x-3 = (6/2)*x // - (6/2)*x
12/x-((6/2)*x)-3 = 0
12/x-3*x-3 = 0
12*x^-1-3*x^1-3*x^0 = 0
(12*x^0-3*x^2-3*x^1)/(x^1) = 0 // * x^2
x^1*(12*x^0-3*x^2-3*x^1) = 0
x^1
12-3*x^2-3*x = 0
12-3*x^2-3*x = 0
DELTA = (-3)^2-(-3*4*12)
DELTA = 153
DELTA > 0
x = (153^(1/2)+3)/(-3*2) or x = (3-153^(1/2))/(-3*2)
x = (3*17^(1/2)+3)/(-6) or x = (3-3*17^(1/2))/(-6)
x in { (3*17^(1/2)+3)/(-6), (3-3*17^(1/2))/(-6)}
x in { (3*17^(1/2)+3)/(-6), (3-3*17^(1/2))/(-6) }
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