If (a_n=3n+4) and (a_m=91), what is (a_{m+12})?
Answer and explanation
Correct answer: 127
Given \(a_n=3n+4\), the common difference of the AP is \(d=3\). Moving 12 terms ahead from \(a_m=91\) increases the value by \(12\times3=36\). Therefore, \(a_{m+12}=91+36=127\). Option 124 would imply an increase of only 33, which is not correct for 12 steps. Exam tip: when the index increases by \(k\), an AP term increases by \(kd\).
Frequently asked questions
What is the correct answer to this question?
127
Why is this the correct answer?
Given \(a_n=3n+4\), the common difference of the AP is \(d=3\). Moving 12 terms ahead from \(a_m=91\) increases the value by \(12\times3=36\). Therefore, \(a_{m+12}=91+36=127\). Option 124 would imply an increase of only 33, which is not correct for 12 steps. Exam tip: when the index increases by \(k\), an AP term increases by \(kd\).
Which subject and chapter does this question cover?
This is a Class 10 Mathematics question. Chapter: Arithmetic Progressions (AP). Topic: Finding the $n$th term of an AP.
