7. (a) Find the first 4 terms, in ascending powers of \(x\), of the binomial expansion of \(( 1 + k x ) ^ { 8 }\), where \(k\) is a non-zero constant. Give each term in its simplest form.
Given that the coefficient of \(x ^ { 3 }\) in this expansion is 1512
(b) find the value of \(k\).