Question

I need help with sigma notations!!! I don't understand how to do any of these at all:(

Answer 1

anybody? please just help me understand how to do these.

Answer 2

put n=3 ,4,5,...,12
and add all

Answer 3

where did those numbers come from?
do you mean like 3-12?

Answer 4

(-5*3-1)+(-5*4-1)+...

Answer 5

ok so i plug numbers 3-12 into -5-n-1 and add the sums?

Answer 6

or 5n

Answer 7

correct

Answer 8

why does it start with 3?

Answer 9

\[\sum_{a}^{b}n\]
we start from a and increase by 1 till we reach b

Answer 10

do you get it?

Answer 11

i got -385

Answer 12

ohhhh ok i get it now! thank you so much!

Answer 13

(-15-1)+(-20-1)+

Answer 14

correct.

Answer 15

yw

Answer 16

wait can you help me with one more? it is different and i don't understand