Answers

2016-07-24T15:48:15+08:00
 a_{n} = a_{1} r ^{n-1} [/tex]
a_{7}  = a_{1}r^{7-6}[/tex]
128 = a_{1}2^{6} [/tex]
128 = a_{1} (64)
 \frac{128}{64} =  \frac{ a_{1} 64}{64}
2 =  a_{1}
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