The first term of an arithmetic sequence is −12 . The common difference of the sequence is 7. What is the sum of the first 30 terms of the sequence?
+23246 Let t1 = first term ---> t1 = -12
Let d = common difference ---> d = 7
Let n = number of terms ---> n = 30
Let t n = nth term ---> tn = t1 + (n - 1)·d ---> t30 = -12 + (30 - 1)·7 ---> t30 = 191
Let S = sum of the terms ---> S = n(t1 + tn)/2 ---> S = 30(-12 + 191)/2 ---> S = your answer
