Odpowiedzi

2010-03-29T23:11:17+02:00
Sn=a₁
S₁=1(1-2)
S₁=-1

a₁+a₂=S₂

S₂=2(2-2)
S=0

-1 + a₂=0
a₂=1

a₂-a₁=r
1+1=r
r=2
5 3 5
Najlepsza Odpowiedź!
2010-03-29T23:19:05+02:00

Sn = n*(n -2) = n² -2n
a1 = S1 = 1² -2*1 = 1 -2 = -1
Sn-1 = (n-1)[(n-1) -2] = (n-1)*(n -3) = n²-4n +3
an = Sn -Sn-1 = n² -2n - (n² -4n +3) = -2n +4n -3 = 2n -3
an+1 = 2*(n +1) - 3 = 2n +2 -3 = 2n -1
r = an+1 - an = 2n -1 -(2n -3) = -1 +3 = 2
Odp. a1 = -1 oraz r = 2
1 1 1