/ 2 7*x\ lim |-1 + 9*x + ---| x->1/3+\ 3 /
Limit(-1 + 9*x^2 + (7*x)/3, x, 1/3)
7/9
= 0.777777777777778
/ 2 7*x\ lim |-1 + 9*x + ---| x->1/3-\ 3 /
0.777777777777778