_________ \/ 3*x + 1 > 3*x
sqrt(3*x + 1) > 3*x
___ 1 \/ 5 [-1/3, - + -----) 6 6
x in Interval.Ropen(-1/3, 1/6 + sqrt(5)/6)
/ ___\ | 1 \/ 5 | And|-1/3 <= x, x < - + -----| \ 6 6 /
(-1/3 <= x)∧(x < 1/6 + sqrt(5)/6)