0580/22 May/Jun 2022, Question 21: Quadratic and Cubic Sequences
Cambridge IGCSE Mathematics 0580 · Paper 22 (Extended) · Calculator · 5 marks
اقرأ هذا الحل مشروحاً بالعربي ←
The question, in short
A sequence has nth term an² + bn − 4, with first term −3 and second term 2. Find the values of a and b.
Summarised in our own words. Use the official paper for the exact wording and any diagrams.
Solution · 5 marks
- 1n = 1: a × 1² + b × 1 − 4 = −3, so a + b = 1
- 2n = 2: a × 2² + b × 2 − 4 = 2, so 4a + 2b = 6, i.e. 2a + b = 3
- 3Subtract: (2a + b) − (a + b) = 3 − 1, so a = 2
- 4b = 1 − 2 = −1
- 5a = 2, b = −1
Answera = 2, b = −1
Stuck on a step? Read the free lesson: Quadratic and Cubic Sequences
Practise more quadratic and cubic sequences questions
Real 0580 past-paper questions, marked on your working like the exam, with a worked solution for every part.
Practise free on LemmaraMore past-paper questions on quadratic and cubic sequences
Also searched as: 0580/22/M/J/22 · 0580_s22_qp_22 · 0580 s22 22 · question 21.
Lemmara is an independent study tool, not affiliated with or endorsed by Cambridge International Education. The worked solutions are Lemmara’s own.