Answers

2016-07-03T16:41:26+08:00
Let n = 1
a1 = 3(1) + 5
a1 = 8

Let n = 12
a12 = 3(12) + 5
a12 = 41

Applying the formula Sn = n(a1 + an)/2
Sn = 12(8+41)/2
Sn = 6(49)
Sn = 294

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