Question

doar ex 4 atat
dau coroana.............​

Answer 1

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: