Write the Word or Phrase That Best Completes Each Statement $\left[ x _ { 1 } , x _ { 2 } \right]$

Short Answer

Write the word or phrase that best completes each statement or answers the question.
Provide the missing information.
-If f is defined on the interval [ $\left[ x _ { 1 } , x _ { 2 } \right]$ ], then the average rate of change of f on the interval [ $\left[ x _ { 1 } , x _ { 2 } \right]$ is
given by the formula .