Question

Find the sum.
-110 + (-102) + (-94) + ... + 66 + 74

Answer 1

Explanation:

a=-110

d=-102-(-110)=-102+110=8

let n be the number of terms.

74=-110+(n-1)×8

74=-110+8n-8

74+118=8n

192=8n

n=192/8=24

`s=(n)/(2) [2a+(n-1)d]\\s=(24)/(2) [2(-110)+(24-1)*8]\\=12[-220+184]\\=12(-36)\\=-432`