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.