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D( x )
x = 0
x = 0
x = 0
x in (-oo:0) U (0:+oo)
1/x-x-(7/3) = 1/7 // - 1/7
1/x-x-(7/3)-(1/7) = 0
1/x-x-7/3-1/7 = 0
1*x^-1-1*x^1-52/21*x^0 = 0
(1*x^0-1*x^2-52/21*x^1)/(x^1) = 0 // * x^2
x^1*(1*x^0-1*x^2-52/21*x^1) = 0
x^1
(-52/21)*x-x^2+1 = 0
(-52/21)*x-x^2+1 = 0
DELTA = (-52/21)^2-(-1*1*4)
DELTA = 4468/441
DELTA > 0
x = ((4468/441)^(1/2)-(-52/21))/(-1*2) or x = (-(-52/21)-(4468/441)^(1/2))/(-1*2)
x = ((4468/441)^(1/2)+52/21)/(-2) or x = (52/21-(4468/441)^(1/2))/(-2)
x in { ((4468/441)^(1/2)+52/21)/(-2), (52/21-(4468/441)^(1/2))/(-2)}
x in { ((4468/441)^(1/2)+52/21)/(-2), (52/21-(4468/441)^(1/2))/(-2) }
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