Question

HELP!!!

Answer 1

Write the sum using summation notation, assuming the suggested pattern continues.

-10 - 2 + 6 + 14 + ... + 110

Answer 2

First, what is the pattern? @mondona

Answer 3

what do you mean? this is a pre lesson and i want to learn

Answer 4

@mondona To put this in summation format we first need to understand what pattern is occurring.

Answer 5

how do i do that @mrdoldum

Answer 6

Well, if we look at the numbers, what do we see? It would help to make everything addition and convert any subtraction to addition of negative numbers. So,

-10+-2+6+14+...+110

How did we get from -10 to -2? -2 to 6? 6 to 14?

Answer 7

+8

Answer 8

Yep, so this website should let you answer it very quickly:

http://www.mathsisfun.com/algebra/sigma-notation.html

Answer 9

after i look at this and i get an answer, can you check it? @mrdoldum

Answer 10

yes. It is difficult to type and explain the stuff on here. That website will be more helpful for describing it than I would be.

Answer 11

yeah i have a program in my class that lets me type it in easily, ill just screenshot it and show you (:

Answer 12

the number on top of the E would be 15 right?

Answer 13

and it would be n=0

Answer 14

right?

Answer 15

\[\sum_{-10}^{110}n+8\]

Answer 16

(-10+8n)

Answer 17

The sequence starts at -10 and goes to 110. That is what the ...+110 means. each number, after the starting number n (-10) is 8 greater than the number preceding it. So, we say the pattern for the summation is n+8.

Answer 18

wow.... definetly not even close to one of my choices @mrdoldum

Answer 19

What are your choices? There are slightly different ways of using sum notation.

Answer 20

Oh, okay. That makes much more sense now. So, one thing you need to know is that horizontal eight means infinity. In this style of notation n is being used as the index number of your summations. So, for n=0 we have just the starting number -10. We then want to add 8. This is our second round (first round was 0) so n=1. We know have \[-10+8(1)\]
What number should be replaced by 1 in \[-10+8(1)\]
Finally, it says continues, so it means never ending. Should you stop at 15 or the horizontal 8 symbol if it just continues?

Answer 21

horizontal 8!

Answer 22

Yep, so what is the answer?

Answer 23

C (: @mrdoldum

Answer 24

Yes.

Answer 25

thank you! there are a couple more but im putting them in separate questions so you get more medals but im doing them on my own first (:

Answer 26

Always best to work through them yourself first.