Răspuns:
C₂ₙⁿ=2C₂ₙ₋₁ⁿ
(2n)!/n!(2n-n)!=2*(2n-1)!/(2n-1-n)!*n!
(2n-1)!*2n/n!*n!=2(2n-1)!/(n-1)!*n!║:(2n-1)!
2n/n!*(n-1)!*n=2/(n-1)!*n!║·n!*(n-1)!=
2n/n=2
2=2
Explicație pas cu pas:
