Find the indicated sum for the arithmetic series. S16 for 12 + 7 + 2 + (-3) + ...
what is the common difference for this series?
not quite - notice that the numbers decrease
yes and Sn = (n/2)[2a1 + (n-1)d] where n = no. of terms, a1 = first term and d = common difference
so pug in your values and work it out
Thank yoou (: