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D( x )
x = 0
x = 0
x = 0
x in (-oo:0) U (0:+oo)
12/x = (8*x)/5 // - (8*x)/5
12/x-((8*x)/5) = 0
(-8/5)*x+12/x = 0
12*x^-1-8/5*x^1 = 0
(12*x^0-8/5*x^2)/(x^1) = 0 // * x^2
x^1*(12*x^0-8/5*x^2) = 0
x^1
(-8/5)*x^2+12 = 0
(-8/5)*x^2+12 = 0
DELTA = 0^2-(4*12*(-8/5))
DELTA = 384/5
DELTA > 0
x = ((384/5)^(1/2)+0)/(2*(-8/5)) or x = (0-(384/5)^(1/2))/(2*(-8/5))
x = -5/16*(384/5)^(1/2) or x = 5/16*(384/5)^(1/2)
x in { -5/16*(384/5)^(1/2), 5/16*(384/5)^(1/2)}
x in { -5/16*(384/5)^(1/2), 5/16*(384/5)^(1/2) }
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