6 In the expansion of \(( 3 + a x ) ^ { n }\), where \(a\) and \(n\) are integers, the coefficient of \(x ^ { 2 }\) is 4860
6
- Show that
$$3 ^ { n } a ^ { 2 } n ( n - 1 ) = 87480$$
[3 marks]
6 - The constant term in the expansion is 729
The coefficient of \(x\) in the expansion is negative.
6
- Verify that \(n = 6\)
6
- (ii) Find the value of \(a\)