SOLUTION: nCn-4=15 find value of n

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Question 1126717: nCn-4=15 find value of n
Answer by ikleyn(52781) About Me  (Show Source):
You can put this solution on YOUR website!
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The left side is  %28n%2A%28n-1%29%2A%28n-2%29%2A%28n-3%29%29%2F%281%2A2%2A3%2A4%29 = %28n%2A%28n-1%29%2A%28n-2%29%2A%28n-3%29%29%2F24.


The equation is


%28n%2A%28n-1%29%2A%28n-2%29%2A%28n-3%29%29%2F24  = 15,    or


n*(n-1)*(n-2)*(n-3) = 24*15 = 360.


The solution is  n = 6.


Check.  C%5B6%5D%5E4 = %286%2A5%2A4%2A3%29%2F24 = 15.   ! Correct !

Solved.