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If .^(9)P(5)+5.^(9)P(4)=.^(10)P(r) , the...

If `.^(9)P_(5)+5.^(9)P_(4)``=.^(10)P_(r)` , then `r` equals

A

3

B

4

C

5

D

6

Text Solution

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The correct Answer is:
C
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