Respostas

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2014-05-08T22:49:59-03:00
2014-05-08T22:54:32-03:00
A1 = 8
an = ?
n = 40
r = 2-8 = -6

an = a1 + (n-1) . r
an = 8 + (40-1) . -6
an = 8 + 39 . (-6)
an = 8 + (-234)
an = -226

S = ( a1 + an ) n /2

S = ( 8 + (-226) . 40 /2

S = ( 8 - 226) . 40

Resposta = -4360
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