1. Help find Sum

find the sum of K 12-57

57
E(Sum) 7-4k
k=12 13

2. Originally Posted by helpless13
find the sum of K 12-57

57
E(Sum) 7-4k
k=12 13
i don't understand what you are trying to write. do you mean $\sum_{k = 12}^{57} \frac {7 - 4k}{13}$ ?

yes that's what i'm trying to write

4. Originally Posted by helpless13
find the sum of K 12-57

57
E(Sum) 7-4k
k=12 13
Would that be:

$
\sum_{k=12}^{57} \frac{7-4k}{13}
$

This is an arithmatic progression with first term $-\ \frac{41}{13}$ (which corresponds to $k=12$), common difference $-\ \frac{4}{13}$ and with $57-12+1 = 46$ terms. You should have a forumla for this.

RonL

5. I do have the formula I just cant get the write answer i dont know what im doing wrong

6. I know you have to take the sum of the first 57 terms and subtract the first 12 but i don't get the correct answer

7. Thanks

Alright thanks for your help i got it now