4MA0 Higher June 2015 Paper 3 Q3
3 The first four terms of an arithmetic sequence are
5 9 13 17
(a) Write down an expression, in terms of \(n\), for the \(n\)th term. (2)
(b) Write down an expression, in terms of \(n\), for the \((n + 1)\)th term. (1)
| Scheme | Marks |
|---|---|
| \(4n + 1\) | M1 A1 |
| (2) |
Notes
M1 A1: M1 \(4n + k\) (\(k\) may be zero)
A1 oe eg. \(5 + (n - 1) \times 4\)
NB: \(n = 4n + 1\) oe scores M1 A0
| Scheme | Marks |
|---|---|
| \(4n + 5\) | B1 |
| (1) |
Notes
B1: ft from (a) if (a) is of the form \(4n + k\) oe
NB: Accept \(4(n + 1) + 1\) oe