Question

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

-4 + 5 + 14 + 23 + ... + 131
Please explain how you got your answer.

Answer 1

what are you adding each time?

Answer 2

9

Answer 3

right
so maybe you can use something like \[\sum_{k=0}^n -4+9k\]

Answer 4

course you still got to figure out what \(n\) is

Answer 5

Im assuming it's infinity considering the other choice I have is 15 and the 15th term would not be 131

Answer 6

\[-4+9n=131\] what is \(n\)?

Answer 7

oh... 15....

Answer 8

ahah. Thanks!

Answer 9

ok so if \[\sum_{k=0}^{15} -4+9k\] is a choice, pick that one

Answer 10

yw

Answer 11

It is. Mind helping me with another?

Answer 12

go ahead and ask, maybe i can helpl

Answer 13

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

16 + 25 + 36 + 49 + ... + n^2 + ...

Answer 14

does it really have \(...\)?

Answer 15

yes

Answer 16

then just go with \[\sum_{n=4}^{\infty}n^2\]

Answer 17

silly because you cannot add all this stuff up but whatever

Answer 18

Why n=4 at the bottom?

Answer 19

what number starts the summation ?

Answer 20

Don't know. Would've said 16.

Answer 21

yes it is

Answer 22

and what number squared gives 16?

Answer 23

4. So It's the square root of the first term that goes on the bottom???

Answer 24

\[\sum_{n=4}^{\infty}n^2=4^2+5^2+6^2+...\]

Answer 25

each term is the square of some number

Answer 26

oh I see

Answer 27

starting with 16, that is the square of 4

Answer 28

Thanks again!

Answer 29

yw again