Answers

2016-07-03T16:41:11+08:00
Sn=n/2[2a1+(n-1)d]
S25=25/2[2(3)+(25-1)14]
S25=12.5[6+24(14)]
S25=12.5[6+336]
S25=12.5(342)
S25=4,275
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