Запишите в виде дроби.1 / (k - 1)! - k / (k + 1)!Очень прошу, помогите!!! 

[latex]\frac{1}{(k-1)!}-\frac{k}{(k+1)!}=\\\\\frac{1}{(k-1)!}-\frac{k}{(k-1)!*k*(k+1)}=\\\\\frac{1}{(k-1)!}-\frac{1}{(k-1)!(k+1)}=\\\\\frac{1*(k+1)-1}{(k-1)!*(k+1)}=\\\\\frac{k+1-1}{(k-1)!(k+1)}=\\\\\frac{k}{(k-1)!(k+1)}[/latex] ======= (или дальше) [latex]=\frac{k*k}{(k-1)!*k(k+1)}=\frac{k^2}{(k+1)!}[/latex]