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D( r )
r = 0
r = 0
r = 0
r in (-oo:0) U (0:+oo)
r-(2/r)-3 = 3/9 // - 3/9
r-(2/r)-(3/9)-3 = 0
r-2*r^-1-1/3-3 = 0
1*r^1-2*r^-1-10/3*r^0 = 0
(1*r^2-10/3*r^1-2*r^0)/(r^1) = 0 // * r^2
r^1*(1*r^2-10/3*r^1-2*r^0) = 0
r^1
r^2+(-10/3)*r-2 = 0
r^2+(-10/3)*r-2 = 0
DELTA = (-10/3)^2-(-2*1*4)
DELTA = 172/9
DELTA > 0
r = ((172/9)^(1/2)-(-10/3))/(1*2) or r = (-(-10/3)-(172/9)^(1/2))/(1*2)
r = ((172/9)^(1/2)+10/3)/2 or r = (10/3-(172/9)^(1/2))/2
r in { (10/3-(172/9)^(1/2))/2, ((172/9)^(1/2)+10/3)/2}
r in { (10/3-(172/9)^(1/2))/2, ((172/9)^(1/2)+10/3)/2 }
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