1MA0 Foundation November 2015 Paper 1 Q18
18 Here are the first four terms of an arithmetic sequence.
11 17 23 29
(a) Find, in terms of \(n\), an expression for the \(n\)th term of this arithmetic sequence. (2)
(b) Is 121 a term of this arithmetic sequence?
You must explain your answer. (2)
You must explain your answer. (2)
| Answer | Mark | Notes |
|---|---|---|
| \(6n + 5\) | 2 | B2 for \(6n + 5\) (B1 for \(6n + k\), where \(k\) is an integer or absent) |
| Answer | Mark | Notes |
|---|---|---|
| no with explanation | 2 | M1 for \(\text{``}6n + 5\text{''} = 121\) or any other valid method, eg counting on 6s to get to 119 (or more) A1 for no with complete explanation, eg \(6n = 116\) will not give a whole number |