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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)
-1/x-(6/(x^2)) = -12 // + 12
12-1/x-(6/(x^2)) = 0
12-1/x-6*x^-2 = 0
12-x^-1-6*x^-2 = 0
t_1 = x^-1
12-6*t_1^2-1*t_1^1 = 0
12-6*t_1^2-t_1 = 0
DELTA = (-1)^2-(-6*4*12)
DELTA = 289
DELTA > 0
t_1 = (289^(1/2)+1)/(-6*2) or t_1 = (1-289^(1/2))/(-6*2)
t_1 = -3/2 or t_1 = 4/3
t_1 = -3/2
x^-1+3/2 = 0
1*x^-1 = -3/2 // : 1
x^-1 = -3/2
-1 < 0
1/(x^1) = -3/2 // * x^1
1 = -3/2*x^1 // : -3/2
-2/3 = x^1
x = -2/3
t_1 = 4/3
x^-1-4/3 = 0
1*x^-1 = 4/3 // : 1
x^-1 = 4/3
-1 < 0
1/(x^1) = 4/3 // * x^1
1 = 4/3*x^1 // : 4/3
3/4 = x^1
x = 3/4
x in { -2/3, 3/4 }
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