1.

The value of sum_(r=1)^(n) (-1)^(r+1)(""^(n)C_(r))/(r+1) is equal to

Answer»

`-1/(N+1)`
`-(1)/(n)`
`(1)/(n+1)`
`(n)/(n+1)`

SOLUTION :`UNDERSET(r=1)overset(n)SUM(-1)^(r+1)(.^(n)C_(r))/((r+1))= (1)/(n+1)underset(r=1)overset(n)sum(-1)^(r+1).^(n+1)C_(r+1)`
`= 1/(n+1)(0-1+(n+1))= (n)/(n+1)`


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