Foundation June 2023 Paper 2R Q19
19 Here are the first four terms of an arithmetic sequence.
38 31 24 17
Find an expression, in terms of \(n\), for the \(n\)th term of the sequence.
(2)
| Scheme | Marks |
|---|---|
| M1 | |
| Correct answer scores full marks (unless from obvious incorrect working) Answer: \(45 - 7n\) | A1 |
| (2) | |
| (2 marks) |
Notes
M1: for \(-7n + k\;(k \neq 45)\) or
\(-7 \times n + k\;(k \neq 45)\) or
\(n \times -7 + k\;(k \neq 45)\)
(\(k\) may be zero or absent or negative)
A1: oe
eg \(45 - 7 \times n\) oe or
\(-7 \times n + 45\) oe or
\(U_n = 45 - 7n\) oe or
\(38 - 7(n - 1)\) oe
NB: award full marks for eg
\(x = 45 - 7n\) oe or
\(n\)th term = \(-7 \times n + 45\) oe or
but only M1 for \(n = 45 - 7n\) oe