Consider the function f(x)=2x36x\displaystyle {f{{\left({x}\right)}}}={2}{x}^{{3}}-{6}{x} on the interval [3,3]\displaystyle {\left[-{3},{3}\right]}. Find the average or mean slope of the function on this interval.  

By the Mean Value Theorem, we know there exists at least one c\displaystyle {c} in the open interval (3,3)\displaystyle {\left(-{3},{3}\right)} such that f(c)\displaystyle {f}'{\left({c}\right)} is equal to this mean slope.
For this problem, there are two values of c\displaystyle {c} that work.

The smaller one is  
and the larger one is