6.
$$\mathrm { f } ( x ) = x ^ { 4 } + x ^ { 3 } + 2 x ^ { 2 } + a x + b ,$$
where \(a\) and \(b\) are constants.
When \(\mathrm { f } ( x )\) is divided by \(( x - 1 )\), the remainder is 7
- Show that \(a + b = 3\)
When \(\mathrm { f } ( x )\) is divided by ( \(x + 2\) ), the remainder is - 8
- Find the value of \(a\) and the value of \(b\).