SOLUTION: Find the sum of -1+2+5+...+(3n-4)

Algebra ->  Sequences-and-series -> SOLUTION: Find the sum of -1+2+5+...+(3n-4)       Log On


   

Question 1053181: Find the sum of -1+2+5+...+(3n-4)
Answer by ikleyn(52788) About Me  (Show Source):
You can put this solution on YOUR website!
.
Apply the formula for the sum of an arithmetic progression.

First term is -1, the common difference is 3, the number of terms is n.

See the lessons
    - Arithmetic progressions
    - The proofs of the formulas for arithmetic progressions
    - Problems on arithmetic progressions
in this site.