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In a sequence, (a_n=2n^2+n). What is the value of (a_6)?
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Answer and explanation
Correct answer: 78
Given \(a_n=2n^2+n\). Substituting \(n=6\), \(a_6=2(6)^2+6=2\times36+6=78\). The option 72 can result from forgetting to add the linear term \(+6\). Exam tip: substitute the value of \(n\) first, then evaluate the exponent carefully.
Frequently asked questions
What is the correct answer to this question?
78
Why is this the correct answer?
Given \(a_n=2n^2+n\). Substituting \(n=6\), \(a_6=2(6)^2+6=2\times36+6=78\). The option 72 can result from forgetting to add the linear term \(+6\). Exam tip: substitute the value of \(n\) first, then evaluate the exponent carefully.
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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