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D( x )
x = 0
x^2 = 0
x = 0
x = 0
x^2 = 0
x^2 = 0
1*x^2 = 0 // : 1
x^2 = 0
x = 0
x in (-oo:0) U (0:+oo)
3/x+2/x-8-5 = 4/(x^2)-(13*x)+40 // - 4/(x^2)-(13*x)+40
13*x+3/x+2/x-(4/(x^2))-40-8-5 = 0
13*x+3/x+2/x-4*x^-2-40-8-5 = 0
13*x^1+5*x^-1-4*x^-2-53*x^0 = 0
(13*x^3-53*x^2+5*x^1-4*x^0)/(x^2) = 0 // * x^4
x^2*(13*x^3-53*x^2+5*x^1-4*x^0) = 0
x^2
13*x^3-53*x^2+5*x-4 = 0
{ 1, -1, 2, -2, 4, -4 }
1
x = 1
13*x^3-53*x^2+5*x-4 = -39
1
-1
x = -1
13*x^3-53*x^2+5*x-4 = -75
-1
2
x = 2
13*x^3-53*x^2+5*x-4 = -102
2
-2
x = -2
13*x^3-53*x^2+5*x-4 = -330
-2
4
x = 4
13*x^3-53*x^2+5*x-4 = 0
4
x-4
13*x^2-x+1
13*x^3-53*x^2+5*x-4
x-4
52*x^2-13*x^3
5*x-x^2-4
x^2-4*x
x-4
4-x
0
13*x^2-x+1 = 0
DELTA = (-1)^2-(1*4*13)
DELTA = -51
DELTA < 0
x in { 4}
x = 4
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