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1. 1 - 1 + 1 - 1 + 1 - 1 +.......+n সংখ্যক পদের যোগফল হবে -
- A. 0
- B. 0
- C. 0
- D. 0
Answer: Option D
Explanation:
a=1
r=−1/1=−1
Sn=a(1−r^n)/1−r
= 1{1−(−1)^n}/1−(−1)
=1−(−1)^n/2
=1/2{1−(−1)^n}
r=−1/1=−1
Sn=a(1−r^n)/1−r
= 1{1−(−1)^n}/1−(−1)
=1−(−1)^n/2
=1/2{1−(−1)^n}
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