Math CentralQuandaries & Queries


Question from Michael, a student:

hope you can help me!

Show that 5 X C(n,5) = n X C(n-1,4)

Hi Michael.

Just expand out the combinations and you will see:

k times C lsub {n} rsub {k}=k times {{n!} over {k!(n-k)!}}

Stephen La Rocque.>

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