In the sequence (20,15,10,5,\ldots), what are the first term and common difference respectively?
Answer and explanation
Correct answer: (20, -5)
The first term of the sequence is 20. The common difference is the second term minus the first term: 15 − 20 = −5, and this difference continues between consecutive terms. Therefore, the correct ordered pair is (20, −5). Option C has the wrong sign for the difference, while options B and D use an incorrect first term. Exam tip: “respectively” means that the answers must be given in the same order as the quantities asked.
Frequently asked questions
What is the correct answer to this question?
(20, -5)
Why is this the correct answer?
The first term of the sequence is 20. The common difference is the second term minus the first term: 15 − 20 = −5, and this difference continues between consecutive terms. Therefore, the correct ordered pair is (20, −5). Option C has the wrong sign for the difference, while options B and D use an incorrect first term. Exam tip: “respectively” means that the answers must be given in the same order as the quantities asked.
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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