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D( x )
x = 0
x = 0
x = 0
x in (-oo:0) U (0:+oo)
12/x-(2*x) = 3/10 // - 3/10
12/x-(2*x)-(3/10) = 0
12/x-2*x-3/10 = 0
12*x^-1-2*x^1-3/10*x^0 = 0
(12*x^0-2*x^2-3/10*x^1)/(x^1) = 0 // * x^2
x^1*(12*x^0-2*x^2-3/10*x^1) = 0
x^1
(-3/10)*x-2*x^2+12 = 0
(-3/10)*x-2*x^2+12 = 0
DELTA = (-3/10)^2-(-2*4*12)
DELTA = 9609/100
DELTA > 0
x = ((9609/100)^(1/2)-(-3/10))/(-2*2) or x = (-(-3/10)-(9609/100)^(1/2))/(-2*2)
x = ((9609/100)^(1/2)+3/10)/(-4) or x = (3/10-(9609/100)^(1/2))/(-4)
x in { ((9609/100)^(1/2)+3/10)/(-4), (3/10-(9609/100)^(1/2))/(-4)}
x in { ((9609/100)^(1/2)+3/10)/(-4), (3/10-(9609/100)^(1/2))/(-4) }
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