Факториал [latex] \frac{9!}{10!-9!} [/latex]

[latex] \frac{9!}{10!-9!}= \frac{9!}{1*2*3*4*5*6*7*8*9*10-1*2*3*4*5*6*7*8*9} = \frac{1*2*3*4*5*6*7*8*9}{1*2*3*4*5*6*7*8*9*(10-1)} [/latex] [latex]= \frac{1}{9} [/latex]