- #1
michonamona
- 122
- 0
Why is the equation
(A) n!/(n-k)! = n(n-1)(n-2)...(n-k+1)
true?
For example, let n=4 and k=2, then
4!/2! = 4x3x2x1 / 2x1 = 4x3 = 12.
I understand this example, but I can't make the connection with this and the right-hand-side of equation (A).
For example, why is our example above not
4!/2! = 4(4-1)(4-2)...(4-2+1).
I know this doesn't make any mathematical sense, but I can't understand how the equation on the right-hand-side of (A) is derived.
Thanks for your help.
M
(A) n!/(n-k)! = n(n-1)(n-2)...(n-k+1)
true?
For example, let n=4 and k=2, then
4!/2! = 4x3x2x1 / 2x1 = 4x3 = 12.
I understand this example, but I can't make the connection with this and the right-hand-side of equation (A).
For example, why is our example above not
4!/2! = 4(4-1)(4-2)...(4-2+1).
I know this doesn't make any mathematical sense, but I can't understand how the equation on the right-hand-side of (A) is derived.
Thanks for your help.
M