Question

What is the sum of the geometric sequence 4, 16, 64, … if there are 8 terms?

Answer 1

Complete solution please

Answer 2

\[\frac{4^9-1}{4-1}\]

Answer 3

General formula?

Answer 4

replace 4 by r

Answer 5

8 by n

Answer 6

that's very helpful satellite (not)

I guess you're being lazy because its the weekend or something

Answer 7

we can start from scratch if you like

Answer 8

Usually, you provide a general formula with an explanation without being voluntold. But if someone respectfully requests a general formula, you should definitely provide it.

Answer 9

actually that is a good point because i was wrong!

Answer 10

As long as people are requesting, I think I should request fro a proof too :P

Answer 11

well it's not "fro" but "for"

Answer 12

\[S=\frac{r^{n+1}-1}{r-1}\]

Answer 13

Can someone just give me an answer

Answer 14

but this one starts at 4 not at 1, so my answer was in fact wrong

Answer 15

87380

Answer 16

THANK YOU