Respostas

2014-03-05T23:06:15-03:00
R=16
A3+A4+A5=12
(A1+2r)+(A1+3r)+(A1+4r)=12
3A1+9r=12
3A1+9(16)=12
3A1+144=12
3A1=12-144
3A1=-132
A1=-44
Sn= (-44+20).5=2x
(-24).5=2x
-120=2x
x=-60
x equivale a soma dos termos
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