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D( x )
x^2+4*x-21 = 0
x^2+4*x-21 = 0
x^2+4*x-21 = 0
x^2+4*x-21 = 0
DELTA = 4^2-(-21*1*4)
DELTA = 100
DELTA > 0
x = (100^(1/2)-4)/(1*2) or x = (-100^(1/2)-4)/(1*2)
x = 3 or x = -7
x in (-oo:-7) U (-7:3) U (3:+oo)
(3*x^2+14*x-89)/(x^2+4*x-21) = 0
3*x^2+14*x-89 = 0
3*x^2+14*x-89 = 0
DELTA = 14^2-(-89*3*4)
DELTA = 1264
DELTA > 0
x = (1264^(1/2)-14)/(2*3) or x = (-1264^(1/2)-14)/(2*3)
x = (4*79^(1/2)-14)/6 or x = (-4*79^(1/2)-14)/6
(x-((-4*79^(1/2)-14)/6))*(x-((4*79^(1/2)-14)/6)) = 0
x^2+4*x-21 = 0
x^2+4*x-21 = 0
DELTA = 4^2-(-21*1*4)
DELTA = 100
DELTA > 0
x = (100^(1/2)-4)/(1*2) or x = (-100^(1/2)-4)/(1*2)
x = 3 or x = -7
(x+7)*(x-3) = 0
((x-((-4*79^(1/2)-14)/6))*(x-((4*79^(1/2)-14)/6)))/((x+7)*(x-3)) = 0
( x-((-4*79^(1/2)-14)/6) )
x-((-4*79^(1/2)-14)/6) = 0 // + (-4*79^(1/2)-14)/6
x = (-4*79^(1/2)-14)/6
( x-((4*79^(1/2)-14)/6) )
x-((4*79^(1/2)-14)/6) = 0 // + (4*79^(1/2)-14)/6
x = (4*79^(1/2)-14)/6
x in { (-4*79^(1/2)-14)/6, (4*79^(1/2)-14)/6 }
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