The value of ( 2 ⋅ 1 P 0 − 3 ⋅ 2 P 1 + 4 ⋅ 3 P 2 − . . . . . . . . up to 51 th…

The value of (21P032P1+43P2........ up to 51th term)+1!2!+3!....... up to 51th term) is equal to 
  1. 1-5151!
  2. 1+51!
  3. 1+52!
  4. 1

Solution

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!

Asked in: JEE Main 2020 (03 Sep Shift 1)

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