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If the rule of a sequence is \(a_n=5\cdot2^{n-1}\), what is the fifth term?
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Answer and explanation
Correct answer: 80
For the fifth term, substitute \(n=5\): \(a_5=5\cdot2^{5-1}=5\cdot2^4=5\cdot16=80\). Therefore, 80 is correct. The value 160 would result from incorrectly using \(2^5\) instead of \(2^{n-1}\). Exam tip: Read the exponent carefully before substituting the term number.
Frequently asked questions
What is the correct answer to this question?
80
Why is this the correct answer?
For the fifth term, substitute \(n=5\): \(a_5=5\cdot2^{5-1}=5\cdot2^4=5\cdot16=80\). Therefore, 80 is correct. The value 160 would result from incorrectly using \(2^5\) instead of \(2^{n-1}\). Exam tip: Read the exponent carefully before substituting the term number.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Sequences and Progressions. Topic: Explicit or general rule.
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