7.
The function f is defined by
$$f ( x ) = \frac { e ^ { 3 x } } { 4 x ^ { 2 } + k }$$
where \(k\) is a positive constant.
- Show that
$$f ^ { \prime } ( x ) = \left( 12 x ^ { 2 } - 8 x + 3 k \right) g ( x )$$
where \(\mathrm { g } ( x )\) is a function to be found.
Given that the curve with equation \(y = \mathrm { f } ( x )\) has at least one stationary point,
- find the range of possible values of \(k\).