17M.1.SL.TZ2.S_1

pestleMathematicsAASLPaper 117M· sl-1-2-arithmetic-sequences-and-seriessource ↗

In an arithmetic sequence, the first term is 3 and the second term is 7.

Find the common difference.

[2]

Find the tenth term.

[2]

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

[2]

Markscheme / solution

* This question is from an exam for a previous syllabus, and may contain minor differences in marking or structure.

attempt to subtract terms (M1)

eg $\,\,\,\,\,$ $d = {u_2} - {u_1},{\text{ }}7 - 3$

$d = 4$ A1 N2

[2 marks]

correct approach (A1)

eg $\,\,\,\,\,$ ${u_{10}} = 3 + 9(4)$

${u_{10}} = 39$ A1 N2

[2 marks]

correct substitution into sum (A1)

eg $\,\,\,\,\,$ ${S_{10}} = 5(3 + 39),{\text{ }}{S_{10}} = \frac{{10}}{2}(2 \times 3 + 9 \times 4)$

${S_{10}} = 210$ A1 N2

[2 marks]

Examiners’ report

[N/A]