Higher November 2020 Unit 2 Q15
15. The first four terms of a sequence are
3, 9, 19, 33, …………
Find the 100th term of the sequence. [3]
| Scheme | Marks | Comments |
|---|---|---|
| \(2n^2 + 1\) or equivalent | B2 | B1 for sight of \(2n^2\) OR for sight of consistent 2nd difference 4. |
| = 20 001 | B1 | FT from their \(2n^2 \pm k\), where \(k \ne 0\) OR from their \(2n^2 \pm an\), where \(a \ne 0\) OR from their \(2n^2 \pm an \pm k\), where \(a \ne 0, k \ne 0\). An unsupported answer of 20 001 gains all 3 marks. If no marks, award SC1 for an unsupported answer of 20 000. |