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1.4 Sequences and Series

1.4 Sequences and Series

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Question 49

The first three terms of a geometric series are (2k+2)(2k+2)(2k+2), (k+4)(k+4)(k+4), and k k\,k respectively, where k k\,k is a positive constant.

a.

Show that k2−6k−16=0k^2 - 6k - 16 = 0k2−6k−16=0.

[4]
b.

Hence show that k=8k = 8k=8.

[2]
c.

Find the common ratio.

[2]
d.

Find the sum to infinity of the series.

[2]
Markscheme

1.4 Sequences and Series Questions

  1. A Level
  2. /Maths
  3. /1.4 Sequences and Series

308 exam-style questions on OCR A Level Maths 1.4 Sequences and Series, covering 1.4.1 Binomial expansion for positive integer n, 1.4.2 Link to binomial probabilities, 1.4.3 Binomial expansion for rational n (A-level only), 1.4.4 Validity of the expansion (A-level only), 1.4.5 Sequences (A-level only), 1.4.6 Increasing, decreasing and periodic sequences (A-level only), 1.4.7 Sigma notation (A-level only), 1.4.8 Arithmetic sequences and series (A-level only), 1.4.9 Geometric sequences and series (A-level only), 1.4.10 Sum to infinity of a geometric series (A-level only), and 1.4.11 Modelling with sequences and series (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.

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