4 The cubic polynomial \(a x ^ { 3 } + b x ^ { 2 } - 3 x - 2\), where \(a\) and \(b\) are constants, is denoted by \(\mathrm { p } ( x )\). It is given that \(( x - 1 )\) and \(( x + 2 )\) are factors of \(\mathrm { p } ( x )\).
- Find the values of \(a\) and \(b\).
- When \(a\) and \(b\) have these values, find the other linear factor of \(\mathrm { p } ( x )\).