Higher November 2017 Paper 6 Q12
12
(a) A sequence is defined using this term-to-term rule.\[u_{n+1} = \sqrt{2u_n + 15}\]
If \(u_1 = 5\), find \(u_2\). [1]
(b) Another sequence is defined using this term-to-term rule,\[u_{n+1} = ku_n + r\]
where \(k\) and \(r\) are constants.
Given that \(u_2 = 41\), \(u_3 = 206\) and \(u_4 = 1031\), find the value of \(k\) and the value of \(r\). [5]
| Answer | Marks | Part marks and guidance | |
|---|---|---|---|
| 5 | 1 | ||
| Answer | Marks | Part marks and guidance | |
|---|---|---|---|
| (\(k\) =) 5 (\(r\) = ) 1 nfww | 5 | B1 for \(206 = 41k + r\) and B1 for \(1031 = 206k + r\) and M1 for \(165k = 825\) and A1 for \(k = 5\) or \(r = 1\) If no or partial method shown, allow full marks for final answer correct | If 0 scored, allow SC2 for final correct answers interchanged Condone attempt to reduce to one variable by sub. or elim. With max of one error |