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x in (-oo:+oo)
Y = (2/3)*x^2-(3*x)-54 // - (2/3)*x^2-(3*x)-54
Y-((2/3)*x^2)+3*x+54 = 0
Y+(-2/3)*x^2+3*x+54 = 0
Y-2/3*x^2+3*x+54 = 0
DELTA = 3^2-(-2/3*4*(Y+54))
DELTA = 8/3*(Y+54)+9
8/3*(Y+54)+9 = 0
8/3*(Y+54)+9 = 0
8/3*Y+153 = 0
8/3*Y+153 = 0
8/3*Y+153 = 0 // - 153
8/3*Y = -153 // : 8/3
Y = -153/8/3
Y = -459/8
DELTA = 0 <=> t_1 = -459/8
x = -3/(-2/3*2) i Y = -459/8
x = 9/4 i Y = -459/8
( x = ((8/3*(Y+54)+9)^(1/2)-3)/(-2/3*2) or x = (-(8/3*(Y+54)+9)^(1/2)-3)/(-2/3*2) ) i Y > -459/8
( x = -3/4*((8/3*(Y+54)+9)^(1/2)-3) or x = 3/4*((8/3*(Y+54)+9)^(1/2)+3) ) i Y > -459/8
Y+459/8 > 0
Y+459/8 > 0 // - 459/8
Y > -459/8
x in { 9/4, -3/4*((8/3*(Y+54)+9)^(1/2)-3), 3/4*((8/3*(Y+54)+9)^(1/2)+3) }
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