Respostas

2014-05-07T17:07:17-03:00
A1= 5
r = ?
an= 8

An= a1+ ( n-1).r
8 = 5+ ( 20-1). r
8= 5+19 . r
19r= 8 - 5
19r = 3
   r= 0,15...
1 3 1