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Class 9MathematicsSequences and ProgressionsSequencesExpertLevel 42
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If (a_n=2^n-n), what will be the value of (a_8)?

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Answer and explanation

Correct answer: 248

Given \(a_n=2^n-n\), substitute \(n=8\): \(a_8=2^8-8=256-8=248\). Therefore, 248 is the correct option. A value such as 240 may result from evaluating the power incorrectly or subtracting at the wrong step. Exam tip: calculate \(2^8=256\) first, then subtract 8.

Related tags

SequencesNth TermExponentsPowersClass 9 Mathematics

Frequently asked questions

What is the correct answer to this question?

248

Why is this the correct answer?

Given \(a_n=2^n-n\), substitute \(n=8\): \(a_8=2^8-8=256-8=248\). Therefore, 248 is the correct option. A value such as 240 may result from evaluating the power incorrectly or subtracting at the wrong step. Exam tip: calculate \(2^8=256\) first, then subtract 8.

Which subject and chapter does this question cover?

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

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10 more MCQs
  1. 1What is the next term of the sequence (2,4,6,8,\ldots)?
  2. 2What is the fifth term of the sequence (5,10,15,20,\ldots)?
  3. 3Which is the fourth term in the sequence (1,3,5,7,\ldots)?
  4. 4What will be the next term of (10,20,30,40,\ldots)?
  5. 5What is the next term of (12,11,10,9,\ldots)?
  6. 6What is the sixth term of (4,8,12,16,\ldots)?
  7. 7What is the third term in (7,14,21,28,\ldots)?
  8. 8What is the next term of (30,27,24,21,\ldots)?
  9. 9The sequence (9,18,27,36,\ldots) consists of multiples of which number?
  10. 10What will be the next term of (100,90,80,70,\ldots)?
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