Exam-style question
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Which answer avoids the common misconception in understand and geometric sequences and series?.
- A.D5: avoid assuming that a term rule and a sum formula answer different questions
- B.Use any familiar GCSE calculation even if it ignores Understand and geometric sequences and series
- C.Write only the final answer without showing the mathematical method
- D.Change the notation or restrictions to make the algebra look simpler
Model answer
What a good answer should say
- The correct answer is D5: avoid assuming that a term rule and a sum formula answer different questions.
- This option is best because identify the term rule, common difference or common ratio before summing, then checks that the notation, restrictions and conclusion match the AQA A-level Mathematics objective.
This answer is tied to the objective: D5 Understand and work with geometric sequences and series, including formulae for the nth term and the sum of a finite geometric series; use the sum to infinity of a convergent geometric series, including the use of |r| < 1 and modulus notation..
Explanation
Why this works
Use the explanation to connect the worked answer back to D5 Understand and work with geometric sequences and series, including formulae for the nth term and the sum of a finite geometric series; use the sum to infinity of a convergent geometric series, including the use of |r| < 1 and modulus notation..
D5: avoid assuming that a term rule and a sum formula answer different questions is the correct option. It directly supports understand and geometric sequences and series by requiring the student to identify the term rule, common difference or common ratio before summing.
The other options are weaker because they hide the reasoning, ignore restrictions, or use a generic calculation that may not fit the objective.
Maths method check
- Topic focus: Pure Mathematics.
- Question style: practice.
- Reasoning demand: recall.
- Check the operation, notation, units, and final answer form against the question before moving on.
Common mistake
No common mistake is linked to this question yet.