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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)
5-(r/(r^2)) = 2*r-35 // - 2*r-35
5-(2*r)-(r/(r^2))+35 = 0
5-2*r-r^-1+35 = 0
40*r^0-2*r^1-1*r^-1 = 0
(40*r^1-2*r^2-1*r^0)/(r^1) = 0 // * r^2
r^1*(40*r^1-2*r^2-1*r^0) = 0
r^1
40*r-2*r^2-1 = 0
40*r-2*r^2-1 = 0
DELTA = 40^2-(-2*(-1)*4)
DELTA = 1592
DELTA > 0
r = (1592^(1/2)-40)/(-2*2) or r = (-1592^(1/2)-40)/(-2*2)
r = (2*398^(1/2)-40)/(-4) or r = (-2*398^(1/2)-40)/(-4)
r in { (2*398^(1/2)-40)/(-4), (-2*398^(1/2)-40)/(-4)}
r in { (2*398^(1/2)-40)/(-4), (-2*398^(1/2)-40)/(-4) }
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