One of the important question from ML Agarwal of Class10 for board examination.
If the nth terms of the two A.P. 9,7,5…. And 24,21,18…. are the same,find the value of n.Also find that term
Class 10, ML Agarwal (avichal publication) arithmetic progression chapter 9, question no. 19
Rajan@2021Guru
If the nth terms of the two A.P. 9,7,5…. And 24,21,18…. are the same,find the value of n.Also find that term
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Clearly 9,7,5,... is an AP with first term a=9 and common difference d=−2 and 24,21,18,.... is an AP with first term A=24 and common difference D=−3.
LetanandAn be the nth term of first and second AP respectively.
Therefore according to question,
an=An
⇒a+(n−1)d=A+(n−1)D
⇒9+(n−1)×−2=24+(n−1)×−3
⇒−2n+11=−3n+27
⇒n=16