Respostas

2014-05-21T20:34:24-03:00
-8 e 13
6+2=8 termos
an=a1(n-1)r
a8=-8(8-1)r
a8=-8+7r
a8-7r=-8
13+8=7r
21=7r
21/7=r
3=r
(-8,-5,-2,1,4,7,10,13)
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1 4 1