Find the indicated partial sum for the given sequence
-s10, 86, 84, 82, 80, ..
A) 770
B) 340
C) -340
D) 950

Question

Quizplus · Accepted Answer

The given sequence is an arithmetic sequence where each term decreases by 2. The first term (s1) is 86, and the common difference (d) is -2. The formula for the sum of the first n terms of an arithmetic sequence is S_n = n/2 * (2a + (n-1)d), where S_n is the sum of the first n terms, n is the number of terms, a is the first term, and d is the common difference. For the 10th partial sum (S_10), n = 10, a = 86, and d = -2. Plugging these values into the formula gives S_10 = 10/2 * (2*86 + (10-1)*(-2)) = 5 * (172 - 18) = 5 * 154 = 770.

Find the Indicated Partial Sum for the Given Sequence