A particular finite difference approximation for the first derivative of a function is f^{\prime}\left(x_{i}\right)=\frac{-f\left(x_{i+3}\right)+9 f\left(x_{i+1}\right)-8 f\left(x_{j}\right)}{6 h} where the points are all equally spaced with a step size h. What

is the order of the truncation error?