Номер 329 пожалуйста!!!!!!!

a) [latex]C^{n+1}_{2n}:C^{n-1}_{2n+1}= \frac{(2n)!}{(n+1)!\cdot (2n-n-1)!}\cdot \frac{(n-1)!\cdot (2n+1-n+1)!}{(2n+1)!}= \frac{n+2}{2n}. \\ \\ \frac{n+2}{2n}= \frac{7}{13} \\ \\ 13(n+2)=2n\cdot 7 \\ \\ n=26[/latex] б) [latex]C^{n}_{2n-1}:C^{n-1}_{2n}= \frac{(2n-1)!}{n!\cdot (2n-1-n)!}\cdot \frac{(n-1)!\cdot (2n-n+1)!}{(2n)!}= \frac{n+1}{2n}. \\ \\ \frac{n+1}{2n}= \frac{9}{17} \\ \\ 17(n+1)=2n\cdot 9 \\ \\ n=17[/latex]