15) Express the series in summation notation, then find the sum if possible.
15+9+27/5+81/25...

See below

Step-by-step explanation:

If you notice a pattern, 15*3/5=9, 9*3/5=27/5, and 27/5*3/5=81/25. So this is an infinite geometric series.

So the common ratio is 3/5 where the first term is 15 and n=1, so the summation notation would be

To find the sum of an infinite geometric series, we use the formula S(n)=a1/1-r where r is the common ratio:

S(n)=15/1-3/5

S(n)=15/2/5

S(n)=75/2

So the sum of the infinite geometric series is therefore 75/2 or 37.5

Hope this helped!

i think the answer is b.

step-by-step explanation:

not 100% sure though.

answer: 5

step-by-step explanation: