Let P_m stand for ^nP_m . Then the expression 1 . P_1 + 2 . P_2 +… - Vidyadip

MCQ

Let $P_m$ stand for $^nP_m$ . Then the expression $1 . P_1 + 2 . P_2 + 3 . P_3 + ..... + n . P_n =$

✓
$(n + 1) ! - 1$
B
$(n + 1) ! + 1$
C
$(n + 1) !$
D
none of these

✓

Answer

Correct option: A.

$(n + 1) ! - 1$

a
$Tn = n . n ! = n ! [ (n + 1) - 1 ] = (n + 1) ! - n !$.

Now put $n = 1, 2, 3 , .......$ and add

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