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Mathematics 8 Online
OpenStudy (rainbow_dash):

One sec.

OpenStudy (swag):

PONYYYYYYYYYYYYYYYYY!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

OpenStudy (rainbow_dash):

\[\sum_{n=1}^{\infty}(3/8)(3/4)^{n-1}\]

OpenStudy (anonymous):

first off pull the \(\frac{3}{8}\) right out front

OpenStudy (anonymous):

\[\frac{3}{8}\sum_{n=1}^{\infty}\left(\frac{3}{4}\right)^{n-1}\]

OpenStudy (rainbow_dash):

okay. what does that do?

OpenStudy (anonymous):

makes it 20% easier.

OpenStudy (anonymous):

it allows you to use the formula for summing a geometric series \[\sum_{k=1}^{\infty}r^{k-1}=\frac{1}{1-r}\]

OpenStudy (rainbow_dash):

Alright. I wish i could give all of you a medal, this has made my day.

OpenStudy (anonymous):

in your case \(r=\frac{3}{4}\)

OpenStudy (anonymous):

with some practice you can do it in your head one minus three fourths is one fourth the reciprocal of one fourth is 4 at the end multiply \(4\times \frac{3}{8}\) because of that pesky \(\frac{3}{8}\) out front

OpenStudy (rainbow_dash):

Ohh mulitply by 3/8 too. thanks :)

OpenStudy (anonymous):

yeah that one is still out front, you can't forget about it

OpenStudy (rainbow_dash):

Cool. Thanks!

OpenStudy (anonymous):

yw

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