If \(a_n=\frac{n(n+4)}{2}\) then what is the value of \(a_8\)?
Answer and explanation
Correct answer: 48
Given \(a_n=\frac{n(n+4)}{2}\). For \(a_8\), substitute \(n=8\): \(a_8=\frac{8(8+4)}{2}=\frac{8\times12}{2}=48\). Hence, 48 is the correct option. Values such as 46 or 50 can result from an arithmetic error, but \(8+4=12\). Exam tip: Substitute the required value of \(n\) first, then simplify step by step.
Frequently asked questions
What is the correct answer to this question?
48
Why is this the correct answer?
Given \(a_n=\frac{n(n+4)}{2}\). For \(a_8\), substitute \(n=8\): \(a_8=\frac{8(8+4)}{2}=\frac{8\times12}{2}=48\). Hence, 48 is the correct option. Values such as 46 or 50 can result from an arithmetic error, but \(8+4=12\). Exam tip: Substitute the required value of \(n\) first, then simplify step by step.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Sequences and Progressions. Topic: Explicit or general rule.
Student feedback
Was this question useful?
👍 0 Helpful 👎 0 Not helpful
Yes 0% No 0%
0 responsesStudent Reviews
No published reviews yet.
