0 reads0 ratings0 helpful
If (a_n=n^2-n), what is the value of (a_5)?
Advertisement
Answer and explanation
Correct answer: \(20\)
Given \(a_n=n^2-n\), substitute \(n=5\): \(a_5=5^2-5=25-5=20\). Hence, \(20\) is correct. \(25\) is only the value of \(5^2\); subtracting \(5\) is also required. Exam tip: substitute the value of \(n\) in every occurrence in the formula.
Frequently asked questions
What is the correct answer to this question?
\(20\)
Why is this the correct answer?
Given \(a_n=n^2-n\), substitute \(n=5\): \(a_5=5^2-5=25-5=20\). Hence, \(20\) is correct. \(25\) is only the value of \(5^2\); subtracting \(5\) is also required. Exam tip: substitute the value of \(n\) in every occurrence in the formula.
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?
Was this question useful?
👍 0 Helpful 👎 0 Not helpful
Difficulty
Easy0%
Medium0%
Hard0%
Was the explanation clear?
Yes 0% No 0%
0 responsesStudent Reviews
No published reviews yet.
Advertisement