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x in (-oo:+oo)
x*((9*(4*x-1))/2) = 15 // - 15
x*((9*(4*x-1))/2)-15 = 0
(9*x*(4*x-1))/2-15 = 0
(9*x*(4*x-1))/2+(-15*2)/2 = 0
9*x*(4*x-1)-15*2 = 0
36*x^2-9*x-30 = 0
36*x^2-9*x-30 = 0
3*(12*x^2-3*x-10) = 0
12*x^2-3*x-10 = 0
DELTA = (-3)^2-(-10*4*12)
DELTA = 489
DELTA > 0
x = (489^(1/2)+3)/(2*12) or x = (3-489^(1/2))/(2*12)
x = (489^(1/2)+3)/24 or x = (3-489^(1/2))/24
3*(x-((3-489^(1/2))/24))*(x-((489^(1/2)+3)/24)) = 0
(3*(x-((3-489^(1/2))/24))*(x-((489^(1/2)+3)/24)))/2 = 0
(3*(x-((3-489^(1/2))/24))*(x-((489^(1/2)+3)/24)))/2 = 0 // * 2
3*(x-((3-489^(1/2))/24))*(x-((489^(1/2)+3)/24)) = 0
( 3 )
3 = 0
x belongs to the empty set
( x-((3-489^(1/2))/24) )
x-((3-489^(1/2))/24) = 0 // + (3-489^(1/2))/24
x = (3-489^(1/2))/24
( x-((489^(1/2)+3)/24) )
x-((489^(1/2)+3)/24) = 0 // + (489^(1/2)+3)/24
x = (489^(1/2)+3)/24
x in { (3-489^(1/2))/24, (489^(1/2)+3)/24 }
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