n = 1 (slider from 0 to 10, step 1)
f(x) = x^(3) + 2 * n * x - 1
A = Intersect(f, xAxis)
texte1: "a_{" + n + "} ≈ " + (x(A))
a(x, y) = (x < 0) ∧ (y > 3)