Hi. I've been having some troubles with a particular integral with Romberg's method plus Richardson's extrapolation.

The integral is:

And the formulas I have are:

Romberg:

Where:

and

And we do it from 0 to 3

Then Richardson to get , and

In the end, I get to a bit far from the real solution. Could it be an error from the method or something wrong with calculations? I've done it a few times but still I can't find a mistake. I'll keep trying though.

Thanks in advance.