Foundation June 2024 Paper 1 Q16

EdexcelFoundationCurrent spec3 marksSequences

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

1 4 7 10

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

The \(n\)th term of a different arithmetic sequence is \(5n + 17\)

(b) Find the 12th term of this sequence. (1)

Mark scheme (a)

Scheme	Marks
	M1
Working not required, so correct answer scores full marks (unless from obvious incorrect working) Answer: \(3n - 2\)	A1
	(2)

Notes

M1: for \(3n + k\) (\(k \neq -2\)) or
\(3 \times n + k\) (\(k \neq -2\)) or
\(n \times 3 + k\) (\(k \neq -2\))
(\(k\) may be zero or absent)

A1: oe eg \(1 + (n - 1)3\) oe or \(3 \times n - 2\) oe or \(n \times 3 - 2\) oe

NB: award full marks for eg
\(x = 3n - 2\) oe or
\(x = 3 \times n - 2\) oe or
\(x = n \times 3 - 2\) oe or
\(n\)th term = \(3n - 2\) oe or
\(n\)th term = \(3 \times n - 2\) oe or
\(n\)th term = \(n \times 3 - 2\) oe or
\(3x - 2\)
Allow eg \(T_n\) or \(U_n\) or \(a_n\) for \(n\)th term
but
only M1 for \(n = 3n - 2\) oe or
\(x = 3x - 2\)

Scheme	Marks
77	B1
	(1)
	(3 marks)