If (a_n=n^2+4n-6), what is the value of (a_{10}-a_6)?
Answer and explanation
Correct answer: 80
Given \(a_n=n^2+4n-6\), \(a_{10}=10^2+4(10)-6=134\) and \(a_6=6^2+4(6)-6=54\). Therefore, \(a_{10}-a_6=134-54=80\). The value 74 can result from an arithmetic error while evaluating \(a_6\) or subtracting. Exam tip: calculate each required term separately before finding their difference.
Frequently asked questions
What is the correct answer to this question?
80
Why is this the correct answer?
Given \(a_n=n^2+4n-6\), \(a_{10}=10^2+4(10)-6=134\) and \(a_6=6^2+4(6)-6=54\). Therefore, \(a_{10}-a_6=134-54=80\). The value 74 can result from an arithmetic error while evaluating \(a_6\) or subtracting. Exam tip: calculate each required term separately before finding their difference.
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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