Find the nth term of: 20, 17, 14, 11, 8, ...
Step 1 Find the common difference
17 − 20 = −3
Common difference d = −3
Step 2 Start the formula
nth term starts with −3n
Step 3 Compare and adjust
−3n gives: −3, −6, −9, −12...
Sequence is: 20, 17, 14, 11...
20 − (−3) = 23, so add 23
Answer: nth term = −3n + 23 (or 23 − 3n)
This study notes covers Worked Example 3: Decreasing Sequence within nth Term for GCSE Mathematics. Revise nth Term in Algebra for GCSE Mathematics with 11 exam-style questions and 4 flashcards. This topic appears regularly enough that it should still be part of a steady revision cycle. It is section 6 of 8 in this topic. Use this study notes to connect the idea to the wider topic before moving on to questions and flashcards.
Practice questions for nth Term
The nth term of a sequence is 3n + 2. What is the 5th term?
A student claims that 50 is a term in the sequence with nth term 3n + 1. Show whether this claim is correct.