SOLUTION: Show that nC1-2nC2+3nC3+...(-1)n+1 nCn=0.
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Question 1038081: Show that nC1-2nC2+3nC3+...(-1)n+1 nCn=0.
Answer by robertb(5830) (Show Source): You can put this solution on YOUR website!
Consider the binomial expansion .
Taking the derivatives of both sides of the preceding equation, we get
.
= .
Now let x = 1:
==> ,
since .
And the identity is proved...
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