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D( u )
u = 0
u = 0
u = 0
u in (-oo:0) U (0:+oo)
(-1/2)*u+4+6 = 6/u+3 // - 6/u+3
(-1/2)*u-(6/u)-3+4+6 = 0
(-1/2)*u-6*u^-1-3+4+6 = 0
7*u^0-1/2*u^1-6*u^-1 = 0
(7*u^1-1/2*u^2-6*u^0)/(u^1) = 0 // * u^2
u^1*(7*u^1-1/2*u^2-6*u^0) = 0
u^1
(-1/2)*u^2+7*u-6 = 0
(-1/2)*u^2+7*u-6 = 0
DELTA = 7^2-(-6*4*(-1/2))
DELTA = 37
DELTA > 0
u = (37^(1/2)-7)/(2*(-1/2)) or u = (-37^(1/2)-7)/(2*(-1/2))
u = 7-37^(1/2) or u = 37^(1/2)+7
u in { 7-37^(1/2), 37^(1/2)+7}
u in { 7-37^(1/2), 37^(1/2)+7 }
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