Question

am nevoie de rezolvat combinarile la mate, va rog!

Answer 1

 

$\displaystyle\bf\\Folosim~formulele:\\\\C_n^p=C_n^{n-p}~~~daca~~p>\frac{n}{2}\\\\\\C_n^p=\frac{A_n^p}{P_p}\\\\Rezolvare:\\\\a)\\C_7^5=C_7^2=\frac{A_7^2}{P_2}=\frac{7\times6}{1\times2}=\frac{42}{2}=21\\\\b)\\C_{10}^9=C_{10}^1=10\\\\c)\\C_{30}^{28}=C_{30}^2=\frac{30\times29}{1\times2}=15\times29=435\\\\\\d)\\C_{50}^2=\frac{50\times49}{1\times2}=25\times49=1225\\\\\\e)\\C_{73}^{73}=C_{73}^0=1$