If \(a_n=\frac{n(n+7)}{4}\), what is the value of \(a_{12}\)?
Answer and explanation
Correct answer: 57
Putting \(n=12\), we get \(a_{12}=\frac{12(12+7)}{4}=\frac{12\times19}{4}=3\times19=57\). Hence, 57 is correct. A value such as 60 can result from incorrectly evaluating \(12+7\) or making an error in multiplication or division. Exam tip: simplify 12 and 4 first, then multiply by 19.
Frequently asked questions
What is the correct answer to this question?
57
Why is this the correct answer?
Putting \(n=12\), we get \(a_{12}=\frac{12(12+7)}{4}=\frac{12\times19}{4}=3\times19=57\). Hence, 57 is correct. A value such as 60 can result from incorrectly evaluating \(12+7\) or making an error in multiplication or division. Exam tip: simplify 12 and 4 first, then multiply by 19.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Sequences and Progressions. Topic: nth term.
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