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JEE MATHEMATICS MCQ: PERMUTATIONS

1 Easy

1 of 1

Application +4 | -1

If

0 < r < s \leq n

and

{ }^n P_r={ }^n P_s

, then value of

r+s

is

View answer and explanation

Correct option: B

2 n-1

Option B (

2n-1

) is correct because the equality of permutations

{}^nP_r = {}^nP_s

with

r < s

implies that

r

and

s

must be

n-1

and

n

respectively.

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