If (a_n=3^n), what is the value of (a_4)?
Answer and explanation
Correct answer: 81
The general term is \(a_n=3^n\). Substituting \(n=4\), we get \(a_4=3^4=3\times3\times3\times3=81\). Therefore, 81 is correct. Note that \(3^3=27\), so choosing 27 would use exponent 3 instead of 4. Exam tip: substitute the term number carefully before evaluating the power.
Frequently asked questions
What is the correct answer to this question?
81
Why is this the correct answer?
The general term is \(a_n=3^n\). Substituting \(n=4\), we get \(a_4=3^4=3\times3\times3\times3=81\). Therefore, 81 is correct. Note that \(3^3=27\), so choosing 27 would use exponent 3 instead of 4. Exam tip: substitute the term number carefully before evaluating the power.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Sequences and Progressions. Topic: Geometric Progression.
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