Question

PLEASE HELP SIGMA NOTATION

Evaluate the summation of negative 5 n minus 1, from n equals 3 to 12..
−410
−385
385
410

Answer 1

@iGreen

Answer 2

@undeadknight26

Answer 3

@TheSmartOne

Answer 4

@Compassionate

Answer 5

so you are going to add terms that look like 5n-1
starting at n=3 all the way to n=12

Answer 6

or if you don't like that you could use
\[\sum_{n=1}^{k}n=\frac{k(k+1)}{2} \\ \sum_{n=1}^{k}c=ck\]
if you rewrite your sum as:
\[\sum_{n=1}^{12}(5n-1) - [5(1)-1]-[5(2)-1]\]

Answer 7

either way