Question 75
Prove that
$$
\sum_{k=1}^{n} (-1)^k \binom{n}{k} \binom{kn}{n} = (-n)^n
$$
$$
\sum_{k=1}^{n} (-1)^k \binom{n}{k} \binom{kn}{n} = (-n)^n
$$
MathNet 2016-part-01 — 184 problems (EN–VI) Question 75
Math Olympiad Vault · MathNet 2016-part-01 — 184 problems (EN–VI)