Răspuns:
Explicație pas cu pas:
1) Cₙ₊₂ⁿ⁺¹ = 3 ; n ∈ N
Cₙ₊₂ⁿ⁺¹ = (n+2)!/(n+1)!(n+2-n-1)! = (n+2)(n+1)!/(n+1)! = n+2 = 3
=> n = 3-2 => n = 1
2) Cₙ¹ = 36 - Aₙ² ; n ∈ N
Cₙ¹ = n! /(n-1)!·1! = n(n-1)! / (n-1)! = n
Aₙ² = n! / (n-2)! = n(n-1)(n-2)! / (n-2)! = n(n-1) =>
n = 36-n(n-1) => n = 36-n²+n => n² = 36 => n = 6
3) 6! / 3! - P₅ = 6·5·4·3! /3! - 5! = 6·5·4 - 5·4·3·2 = 120 - 120 = 0
#copaceibrainly
