21st term of a sequence is. 43 find the sum of first 41 terms.
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Answered by
3
The answer is given below :
Let, the 1st term and the common difference be a and d respectively.
Then,
21st term = 43
=> a + (21 - 1)d = 43
=> a + 20d = 43
=> 2a + 40d = 86 [multiplying by 2]
Hence, the sum of first 41 terms be
= 41/2 {2a + (41 - 1)d}
= 41/2 (2a + 40d)
= 41/2 × 86
= 1763
Thank you for your question.
Let, the 1st term and the common difference be a and d respectively.
Then,
21st term = 43
=> a + (21 - 1)d = 43
=> a + 20d = 43
=> 2a + 40d = 86 [multiplying by 2]
Hence, the sum of first 41 terms be
= 41/2 {2a + (41 - 1)d}
= 41/2 (2a + 40d)
= 41/2 × 86
= 1763
Thank you for your question.
Answered by
2
Answer:
the above answer is correct mate
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