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Question: Answered & Verified by Expert
The value of (21P032P1+43P2........ up to 51th term)+1!2!+3!....... up to 51th term) is equal to 
MathematicsBinomial TheoremJEE MainJEE Main 2020 (03 Sep Shift 1)
Options:
  • A 1-5151!
  • B 1+51!
  • C 1+52!
  • D 1
Solution:
2621 Upvotes Verified Answer
The correct answer is: 1+52!

2·P01=2×1!1!=2!

3·P12=3×2!1!=3!

4·P23=4×3!1!=4!

By this observation given question can be written as

=2!-3!+4!-5!+.......-51!+52!+1!-2!+3!-4!+......-50!+51!

=1!+52!=1+52!

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