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jesusfreak
Find the indicated sum for the arithmetic series. S16 for 12 + 7 + 2 + (-3) + ...
a1=12 d=common difference=-5 a16=a1+(16-1)*d a16=12+15*-5 a16=-63 sum of n terms=n(a1+an)/2 n=16 a1=12 a16=-63 sum=16(12-63)/2 sum=8*(-51)=-408
a1=first term a16=sixteenth term of the series