One of the most important question of ML Agarwal of Class10.
Which term of AP 3,10,17…., will be 84 more than its 13th term?
ML Agarwal (avichal publication) class10, arithmetic progression, chapter9, question no. 18
Rajan@2021Guru
Which term of AP 3,10,17…., will be 84 more than its 13th term
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Clearly, the given sequence is an AP with first term a=3 and common difference d=7.
Let the nth term is 84 more than its 13th term.
⇒an=a13+84
⇒a+(n−1)d=(a+12d)+84
⇒(n−1)d=12d+84
⇒(n−1)7=12×7+84
⇒(n−1)7=7(12+12)
⇒n−1=24
⇒n=25
Therefore 25th term is required term.