Вычисли и запиши ответы

а) \(\dfrac{10!\cdot 8!}{9!\cdot 11!}=\) [ ];

б) \(\dfrac{10!-9!}{9!}=\) [ ];

в) \(\dfrac{89!\cdot 81!}{80!\cdot 90!}=\) [ ];

г) \(\dfrac{89!-88!}{89!+88!} =\) [ ];

д) \(\dfrac{(n+1)!\cdot (n+3)!}{(n+2)!+(n+1)!}=\) [ ];

e) \(\dfrac{(n+1)!-n!}{(n+2)!-(n+1)!} =\) [ ].