Use the values to estimate integral from 0 to 6 using six equal subintervals with left endpoints.

(0, 9.7) (1, 8.9) (2, 8.4) (3, 6.1) (4, 4.5) (5, -6.9) (6, -10.3)

Find the interval on which the curve f(x)=integral of 1/(6+t+t^2)dt from 0 to x is concave downward.