Question

Given the sequence in the table below, determine the sigma notation of the sum for term 4 through term 15.
n an
1 5
2 −10
3 20

Answer 1

@math&ing001

Answer 2

\[\sum_{n=4}^{15}(-1)^{n-1}2a _{n-1}\] with a1=5

Answer 3

Is that what you're looking for ?

Answer 4

\[\sum_{n=4}^{15}5(-2)^{n+1}\]

Answer 5

this is the option most close to yours

Answer 6

Let me check

Answer 7

ok til then i'll write the other options for you

Answer 8

\[\sum_{n=4}^{15}5(-2)^{n-1}\] Does this figure in your choices ?

Answer 9

\[\sum_{n=1}^{15}5(-2)^{n-2} \]
\[\sum_{n=1}^{15}5(-2n)\]
\[\sum_{n=1}^{15}5(-2n)^{n+1}\]

Answer 10

these are the rest of the options

Answer 11

Look at my answer above.

Answer 12

Cause from the sequence given it should be n-1 not n+1

Answer 13

so its the one i typed firrst

Answer 14

Yeah, except 2 should be at the power of n-1

Answer 15

I mean (-2)^(n-1)

Answer 16

ok so its the one n=4? sorry I know I'm annoying

Answer 17

yes :)

Answer 18

Thank You!!

Answer 19

Welcome !

Answer 20

FLVS students:

Answer 21

Actually, Malice it's the first choice : \(\sum_{n=4}^{n=15} 5(-2)^{n-1} \)