Common difference — Algebra I · Grade 9 or accelerated Grade 8, what it means and where it is taught
The constant added each time, in an arithmetic sequence.
Taught in Algebra I · Grade 9 or accelerated Grade 8.
Where it is taught
What it rests on
Work through these first if this one does not settle.
- Arithmetic sequence — A list that grows by adding the same amount each time.
Practise this idea
2 questions in the course bank use Common difference, in Writing & Transforming Linear Functions, Series & Sigma Notation.
Problem 1
Find the common difference of 20, 17, 14, 11, ….
Worked answer
-3
17 - 20 = -3
The sequence is decreasing
Problem 2
The first term is 6 and the sum of the first 10 terms is 195. Find the common difference.
Worked answer
3
195=5(12+9d)
39=12+9d
9d=27 so d=3