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1. what does n! mean and how would you simplify

n!/2(n-2)!

steps would be appreciated
2. n! means n factorial, so it means n multiplied by n-1 multiplied by n-2 etc etc all the way down to one

e.g. 10! = 10x9x8x7x6x5x4x3x2x1
3. (Original post by Triple D)
what does n! mean and how would you simplify

n!/2(n-2)!

steps would be appreciated

Im guessing it simplifies to n(n-1)/2 although I seldom deal with factorials.
4. (Original post by Triple D)
what does n! mean and how would you simplify

n!/2(n-2)!

steps would be appreciated
2(n-2)! = 2(n-2)*(n-3)*(n-4)*...*3*2*1
2(n-2)! = (2n-4)*(2n-6)*(2n-8)*...*3*2*1

But

n*(n-1)*(n-2)*(n-3)*...*3*2*1
-----------------------------
(n-2)*(n-3)*(n-4)*...*3*2*1

Cancels down to:

n*(n-1) = n^2 - n

So n!/2(n-2)! = (n²-n)/2
5. (Original post by Triple D)
what does n! mean and how would you simplify

n!/2(n-2)!

steps would be appreciated
n!=n(n-1)(n-2).....1
(n-2)!=(n-2)(n-3)...1

so u get 1/2 *n(n-1)(n-2)..../(n-2)....

so all the terms cancel except n(n-1) and 1/2
so u get n(n-1)/2
which is wot ralfskini put

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