A sequence has (a_n=6n^2-11n+9). What is the value of (a_{11}-a_5)?
Answer and explanation
Correct answer: 510
Given \(a_n=6n^2-11n+9\), \(a_{11}=6(11)^2-11(11)+9=614\) and \(a_5=6(5)^2-11(5)+9=104\). Therefore, \(a_{11}-a_5=614-104=510\). The value 540 results from incorrectly calculating \(a_5\) as 74. Exam tip: substitute each value of \(n\) carefully and find both terms separately before subtracting.
Frequently asked questions
What is the correct answer to this question?
510
Why is this the correct answer?
Given \(a_n=6n^2-11n+9\), \(a_{11}=6(11)^2-11(11)+9=614\) and \(a_5=6(5)^2-11(5)+9=104\). Therefore, \(a_{11}-a_5=614-104=510\). The value 540 results from incorrectly calculating \(a_5\) as 74. Exam tip: substitute each value of \(n\) carefully and find both terms separately before subtracting.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Sequences and Progressions. Topic: nth term.
Student feedback
Was this question useful?
👍 0 Helpful 👎 0 Not helpful
Yes 0% No 0%
0 responsesStudent Reviews
No published reviews yet.
