Foundation June 2024 Paper 1 Q20
20 Here are the first four terms of an arithmetic sequence.
\[1 \qquad 5 \qquad 9 \qquad 13\]
Find an expression, in terms of \(n\), for the \(n\)th term of this sequence. (2)
| Answer | Mark | Mark scheme |
|---|---|---|
| \(4n - 3\) | B2 | for \(4n - 3\) oe |
| (B1 | for \(4n + k\) where \(k \ne -3\) or is absent unambiguously shown) |
Additional guidance
Accept a different variable eg \(4x - 3\)
Accept \(u_n = 4n - 3,\ T = 4n - 3\) etc
\(n = 4n - 3\) or \(4n^{\text{th}} - 3\) gets B1 only