Find the partial sum.
-Find the sum of the first three terms of the sequence whose general term is $a _ { n } = ( n + 1 ) ( n - 5 )$.
A) 25
B) 65
C) $- 17$
D) $- 25$

Question

Quizplus · Accepted Answer

The first three terms are calculated as follows: $a_1 = (1+1)(1-5) = 2(-4) = -8$, $a_2 = (2+1)(2-5) = 3(-3) = -9$, $a_3 = (3+1)(3-5) = 4(-2) = -8$. The sum is $-8 + (-9) + (-8) = -25$.

Find the Partial Sum an=(n+1)(n−5)a _ { n } = ( n + 1 ) ( n - 5 )an​=(n+1)(n−5)

Find the Partial Sum $a _ { n } = ( n + 1 ) ( n - 5 )$