Consider the cubic function
on
.
The integral is
.
Approximate error in Simpsons rule
.
The first derivative is
.
The second derivative is
.
The third derivative is
.
The fourth derivative is
.
The maximum value of
on the interval
is
.
Substitute
in
.
.
The value of an error is zero.
\Therefore, the Simpsons rule is exact when approximating the integral of a cubic polynomial function.
\The definite integral is
,
.
Consider the function
.
The first derivative is
.
The second derivative is
.
The third derivative is
.
The fourth derivative is
.
The maximum value of
on the interval
is
.
Approximate error in Simpsons rule
.
Substitute
,
and
.
.
The value of an error is zero.
\The Simpsons rule is exact when approximating the integral of a cubic polynomial function.
\Using Simpsons rule the error of
is zero.