The function
$$f ( x ) = \frac { 2 } { 3 } x ^ { 3 } + 2 m x ^ { 2 } + n , \quad m > 0$$
has three distinct real roots.
What is the complete range of possible values of $n$, in terms of $m$ ?
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The function

$$f ( x ) = \frac { 2 } { 3 } x ^ { 3 } + 2 m x ^ { 2 } + n , \quad m > 0$$

has three distinct real roots.

What is the complete range of possible values of $n$, in terms of $m$ ?