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Let A be a set of n (>=3) distinct eleme...

Let A be a set of n `(>=3)` distinct elements. The number of triplets `(x, y, z)` of the A elements in which at least two coordinates is equal to

A

`.^(n)P_(3)`

B

`n^(3)-.^(n)P_(3)`

C

`3n^(2)-2n`

D

`3n^(2)(n-1)`

Text Solution

Verified by Experts

The correct Answer is:
B
Required number of triplets=Total number of triplets without restrictions-number of triplets with all different coordinates
`=n^()-.^(n)P_(3)`
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