If (a_n=5n+14), what is (a_{4p+2})?
Answer and explanation
Correct answer: \(20p+24\)
Given \(a_n=5n+14\), substitute the complete index \(4p+2\) for \(n\): \(a_{4p+2}=5(4p+2)+14=20p+10+14=20p+24\). Therefore, \(20p+24\) is correct. The option \(20p+14\) misses the contribution \(5\times2=10\). Exam tip: when an index is an expression, substitute the entire expression in brackets for \(n\).
Frequently asked questions
What is the correct answer to this question?
\(20p+24\)
Why is this the correct answer?
Given \(a_n=5n+14\), substitute the complete index \(4p+2\) for \(n\): \(a_{4p+2}=5(4p+2)+14=20p+10+14=20p+24\). Therefore, \(20p+24\) is correct. The option \(20p+14\) misses the contribution \(5\times2=10\). Exam tip: when an index is an expression, substitute the entire expression in brackets for \(n\).
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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