[PS] Ex. Notes

semester4/ps/ps-rb/parts/00_prereq.tex

@@ -4,4 +4,9 @@
 $$
     s_n = a_1 \cdot \frac{1-q^n}{1-q} \qquad \underset{n\to\infty}{\lim} s_n = \frac{a_1}{1-q}
 $$
-\subtext{Wobei $a_i = a_1 \cdot q^{i-1}$}
+\subtext{Wobei $a_i = a_1 \cdot q^{i-1}$}
+
+\definition \textbf{Binomialkoeffizient}
+$$
+    \binom{n}{k} := \frac{n!}{k!\cdot(n-k)!}
+$$