Question 592216
We know that


f(-1) = -1
f(0) = 1
f(1) = 1
f(2) = 5
f(3) = 19


And f continually increases after x > 3 (more or less) because its derivative is positive when x > 3.


Since f is continuous everywhere, and the sign of f changes from - to + between -1 and 0, we conclude that there must be a zero in the interval -1 < x < 0. Therefore 0 is the least integral upper bound.