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1.4 Sequences and Series

1.4 Sequences and Series

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Question 11
52%

The second term of a geometric series is 4 and the sum to infinity is 18.

a.

Find the two possible values of rrr.

[2]
b.

Find the corresponding two possible values of aaa.

[2]
c.

Given that r r\,r takes the smaller of the two possible values, find the smallest value of n n\,n for which Sn>17.9S_n > 17.9Sn​>17.9.

[3]
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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