Use the partial sum formula to find the partial sum of the given arithmetic sequence.
-Find 2 + 4 + 6 + 8 + . . ., the sum of the first 40 positive even integers.
A) 1644
B) 1599
C) 1640
D) 1595

Question

Quizplus · Accepted Answer

The sequence is an arithmetic sequence with the first term a = 2, the common difference d = 2, and the number of terms n = 40. The formula for the sum of the first n terms of an arithmetic sequence is S_n = n/2 * (2a + (n-1)d). Plugging in the values, S_40 = 40/2 * (2*2 + (40-1)*2) = 20 * (4 + 78) = 20 * 82 = 1640.

Use the Partial Sum Formula to Find the Partial Sum