Question

Buna!
Cine ma poate ajuta la urmatoarele exercitii?

Answer 1

Răspuns:

A₂₀⁶=20!/6!=7*8*9...*20

A₂₀⁵=20!/5!=6*7*8*9*...*20

A₂₀⁴=5*6*7*8*9*...*20

(7*8*...*20+6*7*8*...*20)/5*6*7*8*...*20=

7*8*...*20(1+6)/5*6*7*8...*20= simplifici prin 7*8*...*20=

7/5*6=7/30

Revin

1a

Notezi fractia cu F1

La numarator (n+1)!+n!=n!(n+1)+n!=n!(n+1+1)=n!(n+2)

F1=n!(n+2)/n!=n+2

b)Notezi fractia cu F2

La numarator (n+1)!=(n-1)!*n*(n+1)

F2=(n-1)!*n*(n+1)/3!*(n-1)!=simplifici prin (n-1)!=

n(n+1)/1*2*3=

Explicație pas cu pas: