1．In the binomial expansion of $$\left( 1 + \frac { 12 n } { 5 } x \right) ^ { n }$$ the coefficients of \(x ^ { 2 }\) and \(x ^ { 3 }\) are equal and non－zero．
（a）Find the possible values of \(n\) ．
（4）
（b）State，giving a reason，which value of \(n\) gives a valid expansion when \(x = \frac { 1 } { 2 }\)
（2）