Question

Find S15 for the geometric series 72 + 12 + 2 + 89821

Answer 1

your last number is what?

Answer 2

you want to find the first 15 sum of that series correct?

Answer 3

your question is messing something!
the ration of the series is 1/6

Answer 4

last number instead of 89821 should be 1/3

Answer 5

the first term is 72
use the formula for the sum

Answer 6

well i suppose so

Answer 7

is it 72+12+2+1/3+1/18+.......

Answer 8

whats the equation to find the answer?

Answer 9

the question is asking you the find \(S_{15}\)
do you know the formula for \(S_n\)

Answer 10

no

Answer 11

104.7

102.5

98.3

86.4

Answer 12

these are answers given

Answer 13

\(\huge \rm Sn=A\frac{1-r^n}{1-r}\) where \(A\) is the first term and \(r\) is the ratio

Answer 14

that the sum formula
you need to find S15

Answer 15

Don't worry about the answers what you should focus on is how to do this

Answer 16

A we said is 72
r=1/6

Answer 17

No go do some arithmetic that's all

Answer 18

So where are we?