If (a_n=2n^2+3), what is the value of (a_3+a_4)?
Answer and explanation
Correct answer: 56
Given \(a_n=2n^2+3\), \(a_3=2(3)^2+3=18+3=21\) and \(a_4=2(4)^2+3=32+3=35\). Therefore, \(a_3+a_4=21+35=56\). The value 52 may result from not including the constant term \(+3\) correctly in both terms. Exam tip: substitute the value of \(n\) and calculate each term separately before adding.
Frequently asked questions
What is the correct answer to this question?
56
Why is this the correct answer?
Given \(a_n=2n^2+3\), \(a_3=2(3)^2+3=18+3=21\) and \(a_4=2(4)^2+3=32+3=35\). Therefore, \(a_3+a_4=21+35=56\). The value 52 may result from not including the constant term \(+3\) correctly in both terms. Exam tip: substitute the value of \(n\) and calculate each term separately before adding.
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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