Validity condition
What Validity condition means in Mathematics A-Level, as defined for AQA, Pearson Edexcel.
Definitions of Validity condition
Exam boards and our study guides word this term in slightly different ways. Learn the version your board uses.
Check what you remember
Read the wording for your board, then hide it and explain Validity condition in your own words. Rough notes are fine. This is a self-check, with no mark or grade.
Reference: Pearson Edexcel
The expansion for rational n is valid only when |bx/a| < 1, which ensures the infinite series converges.
The restriction on x for which a rational binomial expansion represents the original expression, commonly \(|x|<1\) after rewriting.
Topics that use Validity condition
- D: Sequences and series (AQA A-Level)
- Sequences and series (Pearson Edexcel A-Level)
Related terms
- periodic sequence
- increasing sequence
- Arithmetic sequence
- common difference
- Common difference and linear structure
- Convergence and limiting sums
- Convergent geometric series
- Distinguishing between arithmetic and geometric change
Using Validity condition in the exam
Check the command word and mark scheme for your exact question. After comparing your explanation with the reference, use the term in an answer on the linked topic. This practice does not predict an exam mark.
Practise Mathematics questions
Create a free account to answer exam-style questions on this topic and get feedback on your answers.
A week of Premium from your first lesson · Then the free plan continues · No card, no charge