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D( q )
q = 0
q = 0
q = 0
q in (-oo:0) U (0:+oo)
3/q-4 = (2/5)*q // - (2/5)*q
3/q-((2/5)*q)-4 = 0
(-2/5)*q+3/q-4 = 0
3*q^-1-2/5*q^1-4*q^0 = 0
(3*q^0-2/5*q^2-4*q^1)/(q^1) = 0 // * q^2
q^1*(3*q^0-2/5*q^2-4*q^1) = 0
q^1
(-2/5)*q^2-4*q+3 = 0
(-2/5)*q^2-4*q+3 = 0
DELTA = (-4)^2-(3*4*(-2/5))
DELTA = 104/5
DELTA > 0
q = ((104/5)^(1/2)+4)/(2*(-2/5)) or q = (4-(104/5)^(1/2))/(2*(-2/5))
q = -5/4*((104/5)^(1/2)+4) or q = -5/4*(4-(104/5)^(1/2))
q in { -5/4*((104/5)^(1/2)+4), -5/4*(4-(104/5)^(1/2))}
q in { -5/4*((104/5)^(1/2)+4), -5/4*(4-(104/5)^(1/2)) }
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