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x in (-oo:+oo)
0.5 = 0.75*x^2-((t^3)/3) // - 0.75*x^2-((t^3)/3)
(t^3)/3-(0.75*x^2)+0.5 = 0
(t^3)/3-0.75*x^2+0.5 = 0
-0.75*x^2 = -(1/3*t^3+0.5) // : -0.75
x^2 = 1.33333333*(1/3*t^3+0.5)
x^2 = 1.33333333*(1/3*t^3+0.5) // ^ 1/2
abs(x) = 1.33333333^(1/2)*(1/3*t^3+0.5)^(1/2)
x = 1.33333333^(1/2)*(1/3*t^3+0.5)^(1/2) or x = -(1.33333333^(1/2)*(1/3*t^3+0.5)^(1/2))
x in { 1.33333333^(1/2)*(1/3*t^3+0.5)^(1/2), -(1.33333333^(1/2)*(1/3*t^3+0.5)^(1/2)) }
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