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Last updated at May 29, 2018 by Teachoo

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Ex 9.3,6 For what values of x, the numbers (โ2)/7, x, (โ7)/2 are in G.P? Since (โ2)/7, x, (โ7)/2 are in GP So common ratio will be same Common ratio (r) = (๐๐๐๐๐๐ ๐ก๐๐๐ )/(๐น๐๐๐ ๐ก ๐ก๐๐๐) = ๐ฅ/((โ2)/7) = 7๐ฅ/(โ2) Also, Common ratio (r) = (๐โ๐๐๐ ๐ก๐๐๐ )/(๐๐๐๐๐๐ ๐ก๐๐๐) = ((โ7)/2)/๐ฅ = (โ7)/2๐ฅ From (1) & (2) 7๐ฅ/(โ2) = (โ7)/2๐ฅ 7x ร 2x = (-7) ร (-2) 14x2 = 14 x2 = 14/14 x2 = 1 x = ยฑ โ1 x = ยฑ1 So, x = 1 or x = -1 GP is (โ2)/7, x, (โ7)/2 For x = 1, GP is (โ2)/7, 1, (โ7)/2 For x = โ1, GP is (โ2)/7, โ1, (โ7)/2 Hence possible numbers in GP are (โ2)/7, 1, (โ7)/2 or (โ2)/7, โ1, (โ7)/2

Geometric Progression(GP): Formulae based

Ex 9.3, 6
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Example 9

Ex 9.3, 1

Example 10

Ex 9.3, 5

Ex 9.3, 2

Example 11

Ex 9.3, 4

Ex 9.3, 3 Important

Ex 9.3, 17 Important

Example 12

Ex 9.3, 7

Ex 9.3, 10

Ex 9.3, 9

Ex 9.3, 11 Important

Ex 9.3, 8

Ex 9.3, 19

Ex 9.3, 20

Example 13

Ex 9.3, 13

Ex 9.3, 15

Ex 9.3, 16

Ex 9.3, 21

Ex 9.3, 14

Misc 9

Misc 8

Example 14 Important

Ex 9.3, 12

Example 15 Important

Ex 9.3, 18 Important

Misc 21 Not in Syllabus - CBSE Exams 2021

Misc 11

Misc 7 Important

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

About the Author

Davneet Singh

Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 9 years. He provides courses for Maths and Science at Teachoo.