Y by Adventure10, Mango247
Let
be positive integer.Prove the following equality.
![\[ \sum_{r=1}^n (-1)^r\ _n C_r\ \frac{1}{r}=-\sum_{r=1}^n \frac{1}{r} \]](//latex.artofproblemsolving.com/4/0/2/40263db7dae2474de3540974d1d3246590367983.png)

![\[ \sum_{r=1}^n (-1)^r\ _n C_r\ \frac{1}{r}=-\sum_{r=1}^n \frac{1}{r} \]](http://latex.artofproblemsolving.com/4/0/2/40263db7dae2474de3540974d1d3246590367983.png)
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