Higher June 2017 Paper 4 Q19
19
(a) Here are the first four terms of a sequence.\[\frac{1}{2} \qquad \frac{4}{3} \qquad \frac{9}{4} \qquad \frac{16}{5}\]
Find the \(n\)th term of this sequence. [2]
(b) Here are the first four terms of a quadratic sequence, the \(n\)th term of this quadratic sequence is \(an^2 + bn + c\).\[2 \qquad 12 \qquad 28 \qquad 50\]
Find the values of \(a\), \(b\) and \(c\). [4]
| Answer | Marks | Part marks and guidance | |
|---|---|---|---|
| \(\dfrac{n^2}{n + 1}\) | 2 | B1 for \(n^2\) or \(n + 1\) | |
| Answer | Marks | Part marks and guidance | |
|---|---|---|---|
| [\(a =\)] 3 [\(b =\)] 1 [\(c =\)] −2 | 4 | B2 for [\(a =\)] 3 or M1 for second differences = 6 and M1 for revised differences of −1 0 1 2 or B1 for \(b\) or \(c\) correct | accept any correct method see notes |