Question

Discrete Math Question:

Given P (n , 3) = 3*P (n , 2)
What is the value of n ?

Answer 1

Hint: This question uses permutations P(n,r) = n!/(n-r)!

so : n!/(n-3)! = 3 * n!/ (n-2)!

How do we go from here ?

Answer 2

Hint (n-2)!=(n-2)*(n-3)!

Answer 3

Yes! I got the right answer!

@myininaya could you please tell me how did you know (n-2)! = (n-2)(n-3)! ?

Answer 4

$$(n-2)! = (n-2)(n-3)... (3)(2)(1)
\\ ~ \\
(n-2)!= (n-2 ) \left( (n-3)(n-4)... (3)(2)(1)\right)
\\ \, \\
(n-2)!= (n-2 )(n-3)!$$