I need to test the integral bounds for the roots.

6x^3-7x^2+7x+9=0

I used synthetic division to find my answer.

1 6 -7 7 9
6 -1 6
6 -1 6 15

0 6 -7 7 9
0 0 0
6 -7 7 9

-1 6 -7 7 9
-6 13 20
6 -13 20 29

2 6 -7 7 9
12 10 34
6 5 17 43

my answer: -1<x<1
I don't understand why the answer is 2, when by my calculation 1 fits.

correct answer:
-1<x<2