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Date	November 2014	Marks available	2	Reference code	14N.1.sl.TZ0.2
Level	SL only	Paper	1	Time zone	TZ0
Command term	Find	Question number	2	Adapted from	N/A

Question

In an arithmetic sequence, the first term is $2$ and the second term is $5$ .

Find the common difference.

[2]

Find the eighth term.

[2]

Find the sum of the first eight terms of the sequence.

[2]

Markscheme

correct approach (A1)

eg $\;\;\;d = {u_2} - {u_1},{\text{ }}5 - 2$

$d = 3$ A1 N2

[2 marks]

correct approach (A1)

eg $\;\;\;{u_8} = 2 + 7 \times 3$ , listing terms

${u_8} = 23$ A1 N2

[2 marks]

correct approach (A1)

eg $\;\;\;{S_8} = \frac{8}{2}(2 + 23)$ , listing terms, $\frac{8}{2}\left( {2(2) + 7(3)} \right)$

${S_8} = 100$ A1 N2

[2 marks]

Total [6 marks]

Examiners report

All three parts of this question were very well done by the candidates. The occasional mistakes that were seen tended to be arithmetic errors which happened after the candidates had substituted correctly into the formulas given in the formula booklet.

Syllabus sections

Topic 1 - Algebra » 1.1 » Arithmetic sequences and series; sum of finite arithmetic series; geometric sequences and series; sum of finite and infinite geometric series.

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