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Class 9MathematicsSequences and Progressionsnth termEasyLevel 60
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What is the seventh term of the sequence (20,40,60,80,\ldots)?

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Answer and explanation

Correct answer: 140

This is an arithmetic progression with first term 20 and common difference 20. Therefore, \(a_7=20+(7-1)\times20=140\). The number 120 is the sixth term, so it is a close but incorrect option. Exam tip: write the term number or use \(a_n=a+(n-1)d\) to avoid counting errors.

Related tags

Arithmetic ProgressionNth TermSequencesClass 9Common Difference

Frequently asked questions

What is the correct answer to this question?

140

Why is this the correct answer?

This is an arithmetic progression with first term 20 and common difference 20. Therefore, \(a_7=20+(7-1)\times20=140\). The number 120 is the sixth term, so it is a close but incorrect option. Exam tip: write the term number or use \(a_n=a+(n-1)d\) to avoid counting errors.

Which subject and chapter does this question cover?

This is a Class 9 Mathematics question. Chapter: Sequences and Progressions. Topic: nth term.

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10 more MCQs
  1. 1In the sequence (1,4,9,16,...), what is the difference between the 15th term and the 14th term?
  2. 2What is the 25th term of the sequence (-5,-1,3,7,...)?
  3. 3If aₙ = n³ − n, what will be the value of a₇ − a₅?
  4. 4What will be the 12th term in the sequence (3, 5, 9, 15, 23, ...)?
  5. 5If a_n = n(n + 2), what will be the value of a_11 − a_8?
  6. 6If a_n = n^2 + 5n - 2, which term is equal to 148?
  7. 7The sequence (3, 8, 15, 24, …) has general term a_n = n² + 2n. Which term is 168?
  8. 8If a_n = n³ + n², what will be the value of a_6 − a_4?
  9. 9If a_n = 4n² − 1, which term is 575?
  10. 10In the sequence (1, 4, 9, 16, …), what will be the value of a_11 + a_12?
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