The Rule of a Series

1
The Rule of a Series

• Lesson 30

2
The Rule of a Series

• The rule of a series allows you to
• Describe a series
• Calculate a term based on its rank
• Ex. Term 5 x rank 7
• t 5n 7

3

• Variables are represented by symbols.
• These symbols are generally letters.
• Ex. t 4n 3
• Where t is the variable representing the value of
  one term
• n represents the value of the rank
• 4n 4 x n

4
Rule of an arithmetic progression

• Term (common difference) x rank number
• Number 1st term common difference

5
Example

• In the series 45, 49, 53, 57,
• The common difference 4
• The number first term common difference
• 45 4 41
• The Rule
• t 4n 41
• What is the 5th term of this series?
• t 4(5) 41
• 20 41 61

6
Song (The Wheels on the bus)

• The rules of a series equals common difference
  times the rank, times the rank
• The rules of a series equals common difference
  times the rank, plus a number!
• Whats that number? Whats that number?
• 1st term minus common difference
• Whats that number? Whats that number?
• 1st term minus common difference
• T common difference x rank number