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Example 5 - Chapter 9 Class 11 Sequences and Series (Term 1)
Last updated at March 30, 2023 by Teachoo
Examples
Example 1 (i)
Example 1 (ii)
Example 2
Example 3 Important
Example 4 Deleted for CBSE Board 2023 Exams
Example 5 Deleted for CBSE Board 2023 Exams You are here
Example 6 Important Deleted for CBSE Board 2023 Exams
Example 7 Deleted for CBSE Board 2023 Exams
Example 8 Important
Example 9
Example 10 Important
Example 11
Example 12 Important
Example 13
Example 14 Important
Example 15 Important
Example 16
Example 17 Important
Example 18 Important
Example 19 Important Deleted for CBSE Board 2023 Exams
Example 20 Deleted for CBSE Board 2023 Exams
Example 21 Important
Example 22
Example 23
Example 24 Important
Chapter 9 Class 11 Sequences and Series
Serial order wise
- Ex 9.1
- Ex 9.2
- Ex 9.3
- Ex 9.4
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Examples
- Miscellaneous
Transcript
Example 5, If the sum of n terms of an A.P. is nP + 1/2n(n 1)Q , where P and Q are constants, find the common difference. Let a1, a2, an be the given A.P Given, Sum of n terms = nP + 1/2 n (n 1) Q Sn = nP + 1/2 n (n 1) Q Putting n = 1 in (1) S1 = 1 P + 1/2 1 (1 1)Q S1 = P + 1/2(0) S1 = P But sum of first 1 terms will be the first term a1 = S1 = P Sn = nP + 1/2 n (n 1) Q (1) Putting n = 2 in (1) S2 = 2P + 1/2 2(2 1)Q S2 = 2P + 1/2 2 1 Q S2 = 2P + Q Sum of first two terms = First term + Second term S2 = a1 + a2 S2 a1 = a2 a2 = S2 a1 Putting a1 = P , S2 = 2P + Q a2 = 2P + Q P = 2P P + Q = P + Q Thus, a2 = P + Q Common difference (d) = a2 a1 = (P + Q) P = Q Hence, common difference of the given A.P. is Q
