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Example 2 - Chapter 9 Class 11 Sequences and Series (Term 1)
Last updated at Oct. 5, 2021 by Teachoo
Chapter 9 Class 11 Sequences and Series
Concept wise
-
Finding Sequences
- Arithmetic Progression (AP): Formulae based
- Arithmetic Progression (AP): Statement
- Arithmetic Progression (AP): Calculation based/Proofs
- Inserting AP between two numbers
- Arithmetic Mean (AM)
- Geometric Progression(GP): Formulae based
- Geometric Progression(GP): Statement
- Geometric Progression(GP): Calculation based/Proofs
- Inserting GP between two numbers
- Geometric Mean (GM)
- AM and GM (Arithmetic Mean And Geometric mean)
- AP and GP mix questions
- Finding sum from series
- Finding sum from nth number
Transcript
Example 2 What is the 20th term of the sequence defined by an = (n 1) (2 n) (3 + n) ? We need to find 20th term i.e. a20 Let an = (n 1) (2 n) (3 + n) putting n = 20 in (1) a20 = (20 1) (2 20) (3 + 20) = (19) ( 18) (23) = 7866. Hence the 20th term is -7866
