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1.2 Algebra and Functions

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Question 82

A discrete model for the total number of stable configurations, N(k)N(k)N(k), of a crystal lattice with k k\,k layers is given by

N(k)=10k3+11k2+7k+2 N(k) = 10k^3 + 11k^2 + 7k + 2 N(k)=10k3+11k2+7k+2
a.

Use the factor theorem to show that (2k+1)(2k + 1)(2k+1) is a factor of N(k)N(k)N(k).

[2]
b.

Express N(k)N(k)N(k) in the form

N(k)=(2k+1)(ak2+bk+c) N(k) = (2k + 1)(ak^2 + bk + c) N(k)=(2k+1)(ak2+bk+c)

where aaa, b b\,b and c c\,c are constants to be found.

[3]
c.

Given that n n\,n is a positive integer, use your answer to part (b) to explain why 10n3+11n2+7n+210n^3 + 11n^2 + 7n + 210n3+11n2+7n+2 is never prime.

[2]
Markscheme

1.2 Algebra and Functions Questions

  1. A Level
  2. /Maths
  3. /1.2 Algebra and Functions

302 exam-style questions on WJEC A Level Maths 1.2 Algebra and Functions, covering 1.2.1 Algebra and Functions, 1.2.2 Algebra and Functions, 1.2.3 Algebra and Functions, 1.2.4 Algebra and Functions, 1.2.5 Algebra and Functions, 1.2.6 Algebra and Functions, 1.2.7 Algebra and Functions, 1.2.8 Algebra and Functions, 1.2.9 Algebra and Functions, 1.2.10 Algebra and Functions, 1.2.11 Algebra and Functions, and 1.2.12 Algebra and Functions. Each one has a worked solution and a mark scheme showing where the marks go.

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