In which sequence are the terms decreasing by an equal amount but (d) is not (-2)?
Answer and explanation
Correct answer: \(20,17,14,11,\ldots\)
In the sequence \(20,17,14,11,\ldots\), the consecutive differences are \(17-20=-3\) and \(14-17=-3\). Therefore, its common difference is \(d=-3\), not \(-2\). In each of the other three sequences, every next term is 2 less, so \(d=-2\). Exam tip: find the common difference using \(d=a_2-a_1\).
Frequently asked questions
What is the correct answer to this question?
\(20,17,14,11,\ldots\)
Why is this the correct answer?
In the sequence \(20,17,14,11,\ldots\), the consecutive differences are \(17-20=-3\) and \(14-17=-3\). Therefore, its common difference is \(d=-3\), not \(-2\). In each of the other three sequences, every next term is 2 less, so \(d=-2\). Exam tip: find the common difference using \(d=a_2-a_1\).
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Arithmetic Progressions (AP). Topic: Introduction to APs and common difference..
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