find the sum of the first 12th terms of the sequence 8, 5, 2 ......
the difference (d) is -3
so the 12th term is ... 8 + 11(-3) = -25
the 1st and last terms (just like all the other "pairs") sum to -17
6 * -17 = ?
so the 12th term is ... 8 + 11(-3) = -25
the 1st and last terms (just like all the other "pairs") sum to -17
6 * -17 = ?