________ / 2 \/ x + x > 1 - 2*x
sqrt(x^2 + x) > 1 - 2*x
____ 5 \/ 13 (- - ------, oo) 6 6
x in Interval.open(5/6 - sqrt(13)/6, oo)
/ ____ \ | 5 \/ 13 | And|x < oo, - - ------ < x| \ 6 6 /
(x < oo)∧(5/6 - sqrt(13)/6 < x)