If (a_n=5n+6), what is the value of (a_5+a_9)?
Answer and explanation
Correct answer: 82
Given \(a_n=5n+6\), \(a_5=5(5)+6=31\) and \(a_9=5(9)+6=51\). Therefore, \(a_5+a_9=31+51=82\). Option C, 86, is incorrect because direct substitution of the two required values of \(n\) gives 82. Exam tip: find each requested term separately by substituting its value of \(n\) before adding.
Frequently asked questions
What is the correct answer to this question?
82
Why is this the correct answer?
Given \(a_n=5n+6\), \(a_5=5(5)+6=31\) and \(a_9=5(9)+6=51\). Therefore, \(a_5+a_9=31+51=82\). Option C, 86, is incorrect because direct substitution of the two required values of \(n\) gives 82. Exam tip: find each requested term separately by substituting its value of \(n\) before adding.
Which subject and chapter does this question cover?
This is a Class 9 Mathematics question. Chapter: Sequences and Progressions. Topic: Arithmetic Progression.
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