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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+2/x+3+7 = 10*x-4/(x^2)+21 // - 10*x-4/(x^2)+21
1/x-(10*x)+2/x-(-4/(x^2))-21+3+7 = 0
1/x-10*x+2/x+4*x^-2-21+3+7 = 0
3*x^-1-10*x^1+4*x^-2-11*x^0 = 0
(3*x^1-10*x^3-11*x^2+4*x^0)/(x^2) = 0 // * x^4
x^2*(3*x^1-10*x^3-11*x^2+4*x^0) = 0
x^2
3*x-10*x^3-11*x^2+4 = 0
{ 1, -1, 2, -2, 4, -4 }
1
x = 1
3*x-10*x^3-11*x^2+4 = -14
1
-1
x = -1
3*x-10*x^3-11*x^2+4 = 0
-1
x+1
4-10*x^2-x
3*x-10*x^3-11*x^2+4
x+1
10*x^3+10*x^2
3*x-x^2+4
x^2+x
4*x+4
-4*x-4
0
4-10*x^2-x = 0
DELTA = (-1)^2-(-10*4*4)
DELTA = 161
DELTA > 0
x = (161^(1/2)+1)/(-10*2) or x = (1-161^(1/2))/(-10*2)
x = (161^(1/2)+1)/(-20) or x = (1-161^(1/2))/(-20)
x in { (161^(1/2)+1)/(-20), (1-161^(1/2))/(-20), -1}
x in { (161^(1/2)+1)/(-20), (1-161^(1/2))/(-20), -1 }
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