) rules with
and
the generalization to arbitrary n are called Newton-Cotes
formulae (see Abramowitz and Stegun to find them explicitly
written out).
(a)
equidistant
(b)
and/or
(c)
as above, but one omits one or both of the
end-points. The remaining n or n-1 points (
or
or
) are still equidistant.