Question

Please help me! I have a question on sigma notation that I need help with. Attached file below.

Answer 1

@hartnn

Answer 2

does the question really say, find the value of "n"
or is it find the value of "r"
finding n makes no sense...

Answer 3

Sometimes this program I'm using makes really weird mistakes, I'm not sure :/ Because isn't the value of "n" already 1?

Answer 4

its summation,
with every term, value of 'n' changes
like for 1st term, n = 1
for 2nd term, n=2
...
for laste term here, n = 5

but value of 'r' remains the same...

Answer 5

Can you help me solve for "r" then? I really don't understand the steps to solve anything with sigma notation.

Answer 6

getting r is really easy
just compare that with the standard formula
\(\Large a_n=a_1 r^{n-1} \\ \huge (2/9) 3^{n-1}\)
comparing those, its obvious that r= 3 ...

Answer 7

i guess there could be more to this.... but with an unclear question, nothing much can be done

Answer 8

you can find the sum of all 5 terms though..

Answer 9

Thanks for your help! You're always super helpful.

Answer 10

welcome ^_^
always happy to help :)