Use the partial sum formula to find the partial sum of the given arithmetic sequence.
-Find the sum of the first five terms of the arithmetic sequence: -10, -14, -18, . . . .
A) -70
B) 90
C) - 90
D) -42

Question

Quizplus · Accepted Answer

The first term (a1) is -10, the common difference (d) is -4, and the number of terms (n) is 5. The formula for the sum of an arithmetic sequence is S_n = n/2 * (2a1 + (n-1)d). Plugging in the values: S_5 = 5/2 * (2(-10) + 4(-4)) = 5/2 * (-20 - 16) = 5/2 * (-36) = -90.

Use the Partial Sum Formula to Find the Partial Sum