Am nevoie urgent de ajutor, dau coronița❤️

Răspuns:
Explicație pas cu pas:
[tex]C_{n} ^{k} = C_{n} ^{n-k} \\\\ C_{11} ^{9} = C_{11} ^{11-9} = C_{11} ^{2}\\\\C_{11} ^{9} - C_{11} ^{2} = 0[/tex]