SOLUTION: Show that r(nCr) = n[(n-1)C(r-1)]

Question 920291: Show that r(nCr) = n[(n-1)C(r-1)]
Answer by Edwin McCravy(20054) (Show Source): You can put this solution on YOUR website!

By definition 







Write the r! in the denominator on the left as r(r-1)!
Write the n*(n-1)! in the numerator on the right as n!



Cancel the r's on the left:





Both sides are now the same.

Edwin

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