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IB Mathematics: Applications and Interpretation HL · 12.1: Sequences & Series · 12.1.2

Arithmetic series Problem set A Answers

Skills

    1. (a) 1600
    2. (b) −810
    3. (c) 2500

  2. \(5(4 + 9d) = 155\), so \(d = 3\).

    1. (a) 456
    2. (b) 1275
    1. (a) 21 (\(S_{20} = 800\) exactly, \(S_{21} = 882\))
    2. (b) \(n = 22\)

  5. 585

In context

  1. 16 rows; \(8(24 + 9) = 264\) logs.

  2. (a) £1860 (b) Month 32 (\(S_{31} = 2945,\ S_{32} = 3120\))

Stretch

  1. \(u_1 = S_1 = 5\); \(u_n = S_n - S_{n-1} = 6n - 1\).

  2. 50 terms; \(25(6 + 300) = 7650\).

jmaths.xyz · AI HL · 12.1.2 Arithmetic Series