Question

I will medal and fan. Just help me out, for Pete's sake...whoever in the h*ll Pete is...
Write 10 + 6 + 2 + (-2) + (-6) + (-10) + (-14) in sigma notation.

Answer 1

I can convert the Sigma notation to a series. Not the other way around, though.

Answer 2

What is the common difference?

Answer 3

4

Answer 4

(-)4

Answer 5

OK

and the starting value is 10

so
10
10 + 1(-4)
10 + 2(-4)
.
.
10 + n(-4)

Answer 6

Right, OK

Answer 7

note = n starts at ZERO in my sequence.... normally you would start from 1

so last term is (n-1)(-4)

Answer 8

OK, gotch'ya, had to read it a couple of times to process

Answer 9

So...hold on...

Answer 10

\[\Sigma \sum_{\infty}^{n = 1}(10 + n(-4))\]

Answer 11

yea, nay?

Answer 12

Oh, wait, the infinity symbol should be on top, and 'n=1' should be on the bottom...

Answer 13

But you get the point....

Answer 14

\[\sum_{n=1}^{\infty}(10 + n(-4))\]

Answer 15

no - it does not say it's an infinite series

and the first term is 10 so you need to look at my last post...

Answer 16

(if you put n=1 in your expression what do you get for the first term?)

Answer 17

-40

Answer 18

So, negative 40 goes on top?

Answer 19

(Aren't all series infinite?)

Answer 20

whoooooa

you are NEARLY correct

first - it is not an infinite series

so you have a definite limit on top - not infinity

second if you put n=1 in you get 6

so what is the correct expression?

Answer 21

Oh..duh, why did I multiply ten by -4...

OK, then 6 would go on top

Answer 22

no

1+2 = sum from n=1 to n=2 of n

Answer 23

Oh

Answer 24

Wait...
would I just add all the number of terms in the series?

Answer 25

but you are confusing the terms of the series with the enumeration of n

how many terms in the series to get to -14?

then look at the valu of the first term, and correct your expression