_____ 2 \/ 441 - x <= x + 21
-x^2 + sqrt(441) <= x + 21
(-oo, -1] U [0, oo)
x in Union(Interval(-oo, -1), Interval(0, oo))
Or(And(0 <= x, x < oo), And(x <= -1, -oo < x))
((0 <= x)∧(x < oo))∨((x <= -1)∧(-oo < x))