I'm having trouble understanding how to derive an error term for a Newton-Gregory Forward Polynomial which is used in Trapezoid rule and Simpson's rule.
With regard to the Trapezoid rule: Why does the error term use the second derivative of the function rather than finctional differences (which are used in the Newton-Gregory Forward Polynomial). Where in the text book does it show how to derive this error term for a Newton-Gregory Forward Polynomial?
With regards to Simpson's rule: Why does the error term use the 4th derivative rather than the 3rd derivative as Simpson's rule only uses a 3 term Newton-Gregory Forward Polynomial where as the Trapezoid rule only uses 2 terms and the derivative in the errors differs by 2 degrees?