# Simplify sum with binomial coefficients?

How to approach simplifying the following sum: $$\sum_{x=0}^kx\binom{k}{x}\left(\frac{k-x}{k}\right)^d$$ any advice is welcome!

UDP. equation updated, there was a typo.

Ok, after a while, it can be shown that: $\sum_{x=0}^kx\binom{k}{x}\left(\frac{k-x}{k}\right)^d = k\left(1-\frac{1}{k}\right)^d$.