Respostas

2014-05-11T00:21:50-03:00
@7=20 =》 a7= a1+(7-1) R
@10=32 =》 a10=a1+(10-1)R
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20=a1+6R (-1)
32= a1 +9R

12=3R. an =a1+(n-1) R
R=4. n20=?
a1=4 a20= 4+19.4 = 80


2014-05-11T08:03:37-03:00