Find the Derivative of the Function at the Given Value $$f ( x ) = 4 x \cos x ; x = \frac { \pi } { 2 }$$

Short Answer

Find the derivative of the function at the given value of x using a graphing utility. If necessary, round to four decimal
places.
- $$f ( x ) = 4 x \cos x ; x = \frac { \pi } { 2 }$$