Question

помогите мне с факториалами:2k!/(2k+1)! и 1/(k-1)!-1/k!

Answer 1

$1)~,dfrac{(2k)!}{left(2k+1right)!}=dfrac{(2k)!}{left(2k+1right)(2k)!}=dfrac{1}{2k+1}bigskip\2)~,dfrac{1}{left(k-1right)!}-dfrac{1}{k!}=dfrac{1}{left(k-1right)!}-dfrac{1}{kleft(k-1right)!}=dfrac{k-1}{kleft(k-1right)!}=dfrac{left(k-1right)}{kleft(k-1right)left(k-2right)!}=medskip\=dfrac{1}{kleft(k-2right)!}$

Answer 2

спасибо большое