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D( r )
r^2 = 0
r^2 = 0
r^2 = 0
1*r^2 = 0 // : 1
r^2 = 0
r = 0
r in (-oo:0) U (0:+oo)
r^2-(4/(r^2)) = -1 // + 1
r^2-(4/(r^2))+1 = 0
r^2-4*r^-2+1 = 0
t_1 = r^2
1*t_1^1-4*t_1^-1+1 = 0
1*t_1^1-4*t_1^-1+1*t_1^0 = 0
(1*t_1^2+1*t_1^1-4*t_1^0)/(t_1^1) = 0 // * t_1^2
t_1^1*(1*t_1^2+1*t_1^1-4*t_1^0) = 0
t_1^1
t_1^2+t_1-4 = 0
t_1^2+t_1-4 = 0
DELTA = 1^2-(-4*1*4)
DELTA = 17
DELTA > 0
t_1 = (17^(1/2)-1)/(1*2) or t_1 = (-17^(1/2)-1)/(1*2)
t_1 = (17^(1/2)-1)/2 or t_1 = (-(17^(1/2)+1))/2
t_1 in { (-(17^(1/2)+1))/2, (17^(1/2)-1)/2}
t_1 = (-(17^(1/2)+1))/2
r^2-((-(17^(1/2)+1))/2) = 0
r^2+(1/2)*(17^(1/2)+1) = 0
1*r^2 = -(1/2*(17^(1/2)+1)) // : 1
r^2 = -1/2*(17^(1/2)+1)
t_1 = (17^(1/2)-1)/2
r^2-((17^(1/2)-1)/2) = 0
1*r^2 = (17^(1/2)-1)/2 // : 1
r^2 = (17^(1/2)-1)/2
r^2 = (17^(1/2)-1)/2 // ^ 1/2
abs(r) = ((17^(1/2)-1)^(1/2))/(2^(1/2))
r = ((17^(1/2)-1)^(1/2))/(2^(1/2)) or r = -(((17^(1/2)-1)^(1/2))/(2^(1/2)))
r in { ((17^(1/2)-1)^(1/2))/(2^(1/2)), -(((17^(1/2)-1)^(1/2))/(2^(1/2))) }
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