Edexcel A Level Maths: Pure:复习笔记4.5.2 Sigma Notation
Sigma Notation
What is sigma notation?
- The symbol Σ is the capital Greek letter sigma – that's why it's called 'sigma notation'!
- 'Σ' stands for 'sum' – the expression to the right of the Σ tells you what is being summed, and the limits above and below tell you which terms you are summing
- Be careful – the limits don't have to start with 1!
- For example:
- For example:
What do I need to be able to do with sigma notation?
- Sigma notation can be used to represent both arithmetic series and geometric series
- Arithmetic will have the form
- Geometric will have the form
- Writing out the first few terms will help you
- Arithmetic will have the form
- To work out such a sum use the arithmetic and geometric series formulae
- As long as the expressions being summed are the same you can add and subtract in sigma notation
- For example:
Exam Tip
Be careful when more than one letter appears in a sigma notation question. 
Worked Example
转载自savemyexams
国际竞赛真题资料-点击免费领取！
美高学分项目重磅来袭！立即了解
AMC8备考管家服务全新上线！
