5. \(\mathrm { f } ( x ) = x ^ { 3 } - 2 x ^ { 2 } + a x + b\), where \(a\) and \(b\) are constants.
When \(\mathrm { f } ( x )\) is divided by \(( x - 2 )\), the remainder is 1 .
When \(\mathrm { f } ( x )\) is divided by \(( x + 1 )\), the remainder is 28 .
- Find the value of \(a\) and the value of \(b\).
- Show that ( \(x - 3\) ) is a factor of \(\mathrm { f } ( x )\).