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D( x )
5*x-15 = 0
x+3 = 0
5*x-15 = 0
5*x-15 = 0
5*x-15 = 0 // + 15
5*x = 15 // : 5
x = 15/5
x = 3
x+3 = 0
x+3 = 0
x+3 = 0 // - 3
x = -3
x in (-oo:-3) U (-3:3) U (3:+oo)
(x-4)/(5*x-15) = 1/(x+3) // - 1/(x+3)
(x-4)/(5*x-15)-(1/(x+3)) = 0
(x-4)/(5*x-15)-(x+3)^-1 = 0
(x-4)/(5*x-15)-1/(x+3) = 0
((x-4)*(x+3))/((5*x-15)*(x+3))+(-1*(5*x-15))/((5*x-15)*(x+3)) = 0
(x-4)*(x+3)-1*(5*x-15) = 0
x^2-6*x+3 = 0
x^2-6*x+3 = 0
x^2-6*x+3 = 0
DELTA = (-6)^2-(1*3*4)
DELTA = 24
DELTA > 0
x = (24^(1/2)+6)/(1*2) or x = (6-24^(1/2))/(1*2)
x = (2*6^(1/2)+6)/2 or x = (6-2*6^(1/2))/2
(x-((6-2*6^(1/2))/2))*(x-((2*6^(1/2)+6)/2)) = 0
((x-((6-2*6^(1/2))/2))*(x-((2*6^(1/2)+6)/2)))/((5*x-15)*(x+3)) = 0
((x-((6-2*6^(1/2))/2))*(x-((2*6^(1/2)+6)/2)))/((5*x-15)*(x+3)) = 0 // * (5*x-15)*(x+3)
(x-((6-2*6^(1/2))/2))*(x-((2*6^(1/2)+6)/2)) = 0
( x-((2*6^(1/2)+6)/2) )
x-((2*6^(1/2)+6)/2) = 0 // + (2*6^(1/2)+6)/2
x = (2*6^(1/2)+6)/2
( x-((6-2*6^(1/2))/2) )
x-((6-2*6^(1/2))/2) = 0 // + (6-2*6^(1/2))/2
x = (6-2*6^(1/2))/2
x in { (2*6^(1/2)+6)/2, (6-2*6^(1/2))/2 }
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