Odpowiedzi

2010-01-04T12:46:17+01:00
A2+a5-a3=10
a2+a9=17

a1+r + a1+4r -(a1+2r) = 10
a1+r + a1+8r = 17

a1+r+a1+4r-a1-2r = 10
2a1 + 9r = 17

a1+3r=10
2a1 + 9r = 17

a1=10-3r
2(10-3r) + 9r = 17

20-6r+9r = 17
3r= 17-20
3r=-3
r=-1

a1= 10- 3* (-1)
a1= 10+3
a1=13

an= a1+ r(n-1)
an= 13 -1(n-1)
an= 13-n+1
an= 14-n