Question

how do you find the
Geometric sum of 24+12+6+3 . . .

Answer 1

If a and b are positive integers such that ab = 125, then (a-b)^(a+b-4) is equal to ?

Answer 2

I don't know what that means haha im super confused

Answer 3

Rule of the sum:\[24*\sum_{0}^{\infty} 1/2^n\]
Nifty trick for geometric series with initial number a and ratio r:\[24*\sum_{0}^{\infty} 1/2^n = a/(1-r) = 24/(1-1/2) = 48\]

Answer 4

well you got the right answer. i just don't understand it

Answer 5

The trick is:
\[a*\sum_{0}^{\infty}(r)^n = a/(1-r)\]
As long as -1 < r < 1

Answer 6

i used S = t1 / 1-r

Answer 7

but i got 12

Answer 8

That's the same thing :D

Answer 9

then how did I get 12? hahaha

Answer 10

You multiplied by 1/2 instead of divided
24/(1/2) = 48, not 12

Answer 11

OHHHHH

Answer 12

wow that was embarassing hahaha

Answer 13

thanks daniel :)

Answer 14

No it isn't. I do that all the time :D

Answer 15

No worries :D

Answer 16

i actually need a lot more help

Answer 17

if youve got some extra time :D