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Mathematics 15 Online
OpenStudy (anonymous):

Find the sum of the infinite geometric series, if it exists. 1/2 -2+ 8 -...

ganeshie8 (ganeshie8):

see any pattern ?

ganeshie8 (ganeshie8):

1/2 -2 8 what next ?

OpenStudy (anonymous):

times -4?

ganeshie8 (ganeshie8):

Yes!

OpenStudy (anonymous):

here's my answer choices...

OpenStudy (anonymous):

a.-8192 b.1/10 c.32,768 d.does not exist

ganeshie8 (ganeshie8):

so the common ratio is \(-4\) what do you know about the condition for convergence of geometric series ?

OpenStudy (anonymous):

off of the top of my head, nothing. im overwhlemed so thanks for your patience.

OpenStudy (anonymous):

so d is my answer? because if its not. what am i missing or doing wrong?

ganeshie8 (ganeshie8):

Notice that the terms itself are alternating and blowing up : 1/2 -2 8 -32 128 ..... . so intuitively it appears that the sum must not converge, that is the sum `does not exist`

OpenStudy (anonymous):

ok i see. thank you!

ganeshie8 (ganeshie8):

if you look up ur notes, im sure you will find a nice criterian for convergence of geometric series

OpenStudy (anonymous):

we aren't using a book. just worksheets with formulas on them.

OpenStudy (anonymous):

thank you, i really appreciate your help.

OpenStudy (jhannybean):

http://seriestestmjs.weebly.com/uploads/1/1/5/7/11577982/2663460_orig.jpg That might help you :)

OpenStudy (anonymous):

@Jhannybean thanks love! i appreciate it!

ganeshie8 (ganeshie8):

Here is the test for geometric series : If the common ratio is between -1 and 1, then the sum converges, otherwise the sum doesn't converge.

OpenStudy (anonymous):

@ganeshie8 ok i see, i see.

OpenStudy (dan815):

|dw:1439181519693:dw|

ganeshie8 (ganeshie8):

goes wid the caption ;) |dw:1439181598024:dw|

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