Upgrade subject to access all content

Find the locations and type of all relative extrema for the function,

$$f( x ) ={ 2x }^{ 3 }+{ 4x }^{ 2 }-8x-11$$

$f(x)$ has a relative maximum at $x=-\cfrac{1}{2}$

$f(x)$ has a relative minimum at $x=\cfrac{2}{3}$

$f(x)$ has a relative maximum at $-\cfrac{2}{3}$ and a relative minimum at $x=4$.

$f(x)$ has a relative maximum at $x=-2$ and a relative minimum at $x=\cfrac{2}{3}$