If \(a_n=\frac{n(n+3)}{2}\), what is the value of \(a_3\)?
Answer and explanation
Correct answer: 9
For the third term, substitute \(n=3\): \(a_3=\frac{3(3+3)}{2}=\frac{3\times6}{2}=9\). Therefore, the correct answer is 9. The value 12 may result from forgetting to divide by 2. Exam tip: substitute the term number carefully into the general term and simplify step by step.
Frequently asked questions
What is the correct answer to this question?
9
Why is this the correct answer?
For the third term, substitute \(n=3\): \(a_3=\frac{3(3+3)}{2}=\frac{3\times6}{2}=9\). Therefore, the correct answer is 9. The value 12 may result from forgetting to divide by 2. Exam tip: substitute the term number carefully into the general term and 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.
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