If \(a_n=\frac{n(5n-1)}{2}\), what is the value of \(a_6\)?
Answer and explanation
Correct answer: 87
Substitute \(n=6\): \(a_6=\frac{6(5\times6-1)}{2}=\frac{6(30-1)}{2}=\frac{6\times29}{2}=87\). Hence, the correct answer is 87. A value such as 84 can result from an error while evaluating \(5n-1\). Exam tip: substitute the term number first, then simplify the bracket and perform multiplication and division step by step.
Frequently asked questions
What is the correct answer to this question?
87
Why is this the correct answer?
Substitute \(n=6\): \(a_6=\frac{6(5\times6-1)}{2}=\frac{6(30-1)}{2}=\frac{6\times29}{2}=87\). Hence, the correct answer is 87. A value such as 84 can result from an error while evaluating \(5n-1\). Exam tip: substitute the term number first, then simplify the bracket and perform multiplication and division 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.
