Answers

2015-07-23T10:55:52+08:00
Using the formula for the sum of arithmetic sequence you'll have
Sn = [2A1 + (n-1) d] n/2
the first term would be 2
n = 12
d = 2
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Sn = [2(2) + (12-1)(2)] (12/2)
Sn = [4 + 11 (2)](6)
Sn = [4 + 22](6)
Sn = 26 (6)
Sn = 156
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