SOLUTION: I have stared at my notes for at least and hour and I have gone no where, could you please help me! Use summation notation to write the series 42+34+26+... for 8 terms. Then evalu

Algebra ->  Sequences-and-series -> SOLUTION: I have stared at my notes for at least and hour and I have gone no where, could you please help me! Use summation notation to write the series 42+34+26+... for 8 terms. Then evalu      Log On


   



Question 452857: I have stared at my notes for at least and hour and I have gone no where, could you please help me!
Use summation notation to write the series 42+34+26+... for 8 terms. Then evaluate it.

Answer by richard1234(7193) About Me  (Show Source):
You can put this solution on YOUR website!
The series is arithmetic with common difference -8. We can determine that the nth term is given by and express the sum of the first eight terms in sigma notation:



There are multiple ways to evaluate the sum without using a calculator. Perhaps the easiest way is to manipulate the expression inside the sum:



The sum is simply 50 added eight times, or 400. The sum is equal to . Hence,