What is the explicit rule of the sequence (12,24,36,48,\ldots)?
Answer and explanation
Correct answer: \(a_n=12n\)
This is an arithmetic sequence with first term 12 and common difference 12. For \(n=1\), \(a_n=12n=12\); for \(n=2\), it gives 24; and for \(n=3\), it gives 36. Hence, the correct explicit rule is \(a_n=12n\). The rule \(a_n=24n\) would give 24 as the first term, so it is incorrect. Exam tip: substitute \(n=1\) and \(n=2\) to check an explicit rule.
Frequently asked questions
What is the correct answer to this question?
\(a_n=12n\)
Why is this the correct answer?
This is an arithmetic sequence with first term 12 and common difference 12. For \(n=1\), \(a_n=12n=12\); for \(n=2\), it gives 24; and for \(n=3\), it gives 36. Hence, the correct explicit rule is \(a_n=12n\). The rule \(a_n=24n\) would give 24 as the first term, so it is incorrect. Exam tip: substitute \(n=1\) and \(n=2\) to check an explicit rule.
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.
