6. Given that the binomial expansion, in ascending powers of \(x\), of
$$\frac { 6 } { \sqrt { } \left( 9 + A x ^ { 2 } \right) } , \quad | x | < \frac { 3 } { \sqrt { } | A | }$$
is \(\quad B - \frac { 2 } { 3 } x ^ { 2 } + C x ^ { 4 } + \ldots\)
- find the values of the constants \(A , B\) and \(C\).
- Hence find the coefficient of \(x ^ { 6 }\)