Ex 8.2, 15 - Chapter 8 Class 11 Sequences and Series
Last updated at April 16, 2024 by Teachoo
Geometric Progression(GP): Formulae based
Example 4
Ex 8.2, 1
Example 5 Important
Ex 8.2, 5 (a)
Ex 8.2, 2
Example 6
Ex 8.2, 4
Ex 8.2, 3 Important
Ex 8.2, 17 Important
Example 7 Important
Ex 8.2, 7 Important
Ex 8.2, 10
Ex 8.2, 9 Important
Ex 8.2, 11 Important
Ex 8.2, 8
Ex 8.2, 19
Ex 8.2, 20
Example 8
Ex 8.2, 13
Ex 8.2, 15 You are here
Ex 8.2, 16 Important
Ex 8.2, 21
Ex 8.2, 14 Important
Misc 3
Misc 2
Example 9 Important
Ex 8.2, 12
Example 10 Important
Ex 8.2, 18 Important
Misc 11 (i) Important
Misc 5
Misc 1 Important
Geometric Progression(GP): Formulae based
Last updated at April 16, 2024 by Teachoo
Ex9.3, 15 Given a G.P. with a = 729 and 7th term 64, determine S7. First term a = 729 and 7th term = 64 we know that nth term of G.P. = arn-1 a7 = ar6 putting values 64 = 729 r6 64/729 = r6 2^6/3^6 = r6 (2/3)^6= r6 (2/3)^6= r6 Comparing powers r = 2/3 We need to find sum of first 7 terms We know that Sum of n terms = (1 ^ )/(1 ) Sn = (1 ^ )/(1 ) S7 = (1 7)/(1 ) Putting values S7 = 729(1 (2/3)^7 )/(1 2/3) S7 = 729(1 (2/3)^7 )/(1 2/3) S7 = 729(1 128/2187)/((3 2)/3) S7 = 729(1 128/2187)/(1/3) S7 = 729(2059/2187) 3 S7 = 2187(2059/2187) S7 = 2059 Hence S7 = 2059 Hence, sum of first 7 terms is 2059