Foundation June 2022 Paper 1 Q16

EdexcelFoundationCurrent spec3 marksSequences

16 Here are the first five terms of an arithmetic sequence.

1 5 9 13 17

(a) Find an expression, in terms of \(n\), for the \(n\)th term of this sequence. (2)

The \(n\)th term of another arithmetic sequence is \(3n + 5\)

(b) Find an expression, in terms of \(m\), for the \((2m)\)th term of this sequence. (1)

Mark scheme (a)

Scheme	Marks
	M1
\(4n - 3\)	A1
	(2)

Notes

M1: for \(4n + k\;(k \neq -3)\) or
\(4 \times n + k\;(k \neq -3)\) or
\(n \times 4 + k\;(k \neq -3)\)
(\(k\) may be zero or absent)

A1: oe e.g. \(1 + (n - 1)4\) oe or \(4 \times n - 3\) oe or \(n \times 4 - 3\) oe
NB: award full marks for eg
\(x = 4n - 3\) oe or \(x = 4 \times n - 3\) oe or
\(x = n \times 4 - 3\) oe or \(n\)th term \(= 4n - 3\) oe or
\(n\)th term \(= 4 \times n - 3\) oe or
\(n\)th term \(= n \times 4 - 3\) oe
but only M1 for \(n = 4n - 3\) oe

Scheme	Marks
\(6m + 5\)	B1
	(1)
	(3 marks)