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Ex 9.3, 2 - Find 12th term of GP whose 8th term is 192 - Geometric Progression(GP): Formulae based

  1. Chapter 9 Class 11 Sequences and Series
  2. Serial order wise
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Ex9.3,2 Find the 12th term of a G.P. whose 8th term is 192 and the common ratio is 2. We know that an = arn – 1 where an = nth term of GP n is the number of terms a is the first term r is the common ratio Here, common ratio r = 2 & 8th term is 192 i.e. a8 = 192 Putting an = 192, r = 2 and n = 8 in an 192 = a 2^(8−1) 192 = a × 27 192/27 = a a = 192/27 Now we need to find 12th term, we use the formula an = arn – 1 Putting n = 12 , a = 192/27 , r = 2 a12 = 192/27 × (2)12 – 1 = 192/27 × (2)11 = 192(2)11 – 7 = 192(2)4 = 192 × 16 = 3072 Thus, 12th term is 3072

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