Write the Word or Phrase That Best Completes Each Statement $$f ( x ) = 4 x \cos x ; x = \frac { \pi } { 2 }$$

Short Answer

Write the word or phrase that best completes each statement or answers the question.
Find the derivative of the function at the given value of x using a graphing utility. If necessary, round to four decimal
places.
- $$f ( x ) = 4 x \cos x ; x = \frac { \pi } { 2 }$$