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D( x )
x^2-1 = 0
x+1 = 0
x^2-1 = 0
x^2-1 = 0
1*x^2 = 1 // : 1
x^2 = 1
x^2 = 1 // ^ 1/2
abs(x) = 1
x = 1 or x = -1
x+1 = 0
x+1 = 0
x+1 = 0 // - 1
x = -1
x in (-oo:-1) U (-1:1) U (1:+oo)
(4*x+1)/(x+1) = 12/(x^2-1) // - 12/(x^2-1)
(4*x+1)/(x+1)-(12/(x^2-1)) = 0
(4*x+1)/(x+1)-12*(x^2-1)^-1 = 0
(4*x+1)/(x+1)-12/(x^2-1) = 0
((4*x+1)*(x^2-1))/((x+1)*(x^2-1))+(-12*(x+1))/((x+1)*(x^2-1)) = 0
(4*x+1)*(x^2-1)-12*(x+1) = 0
4*x^3+x^2-16*x-13 = 0
4*x^3+x^2-16*x-13 = 0
4*x^3+x^2-16*x-13 = 0
{ 1, -1, 13, -13 }
1
x = 1
4*x^3+x^2-16*x-13 = -24
1
-1
x = -1
4*x^3+x^2-16*x-13 = 0
-1
x+1
4*x^2-3*x-13
4*x^3+x^2-16*x-13
x+1
-4*x^3-4*x^2
-3*x^2-16*x-13
3*x^2+3*x
-13*x-13
13*x+13
0
4*x^2-3*x-13 = 0
DELTA = (-3)^2-(-13*4*4)
DELTA = 217
DELTA > 0
x = (217^(1/2)+3)/(2*4) or x = (3-217^(1/2))/(2*4)
x = (217^(1/2)+3)/8 or x = (3-217^(1/2))/8
x in { (3-217^(1/2))/8, (217^(1/2)+3)/8, -1}
(x-((3-217^(1/2))/8))*(x-((217^(1/2)+3)/8))*(x+1) = 0
((x-((3-217^(1/2))/8))*(x-((217^(1/2)+3)/8))*(x+1))/((x+1)*(x^2-1)) = 0
((x-((3-217^(1/2))/8))*(x-((217^(1/2)+3)/8))*(x+1))/((x+1)*(x^2-1)) = 0 // * (x+1)*(x^2-1)
(x-((3-217^(1/2))/8))*(x-((217^(1/2)+3)/8))*(x+1) = 0
( x+1 )
x+1 = 0 // - 1
x = -1
( x-((217^(1/2)+3)/8) )
x-((217^(1/2)+3)/8) = 0 // + (217^(1/2)+3)/8
x = (217^(1/2)+3)/8
( x-((3-217^(1/2))/8) )
x-((3-217^(1/2))/8) = 0 // + (3-217^(1/2))/8
x = (3-217^(1/2))/8
x in { -1}
x in { (217^(1/2)+3)/8, (3-217^(1/2))/8 }
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