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D( x )
x = 0
x = 0
x = 0
x in (-oo:0) U (0:+oo)
4/x-((18/5)*x) = 2 // - 2
4/x-((18/5)*x)-2 = 0
(-18/5)*x+4/x-2 = 0
4*x^-1-18/5*x^1-2*x^0 = 0
(4*x^0-18/5*x^2-2*x^1)/(x^1) = 0 // * x^2
x^1*(4*x^0-18/5*x^2-2*x^1) = 0
x^1
(-18/5)*x^2-2*x+4 = 0
(-18/5)*x^2-2*x+4 = 0
DELTA = (-2)^2-(4*4*(-18/5))
DELTA = 308/5
DELTA > 0
x = ((308/5)^(1/2)+2)/(2*(-18/5)) or x = (2-(308/5)^(1/2))/(2*(-18/5))
x = -5/36*((308/5)^(1/2)+2) or x = -5/36*(2-(308/5)^(1/2))
x in { -5/36*((308/5)^(1/2)+2), -5/36*(2-(308/5)^(1/2))}
x in { -5/36*((308/5)^(1/2)+2), -5/36*(2-(308/5)^(1/2)) }
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