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#1

$Old$ October 27th, 2007, 03:22 PM

beetz $beetz is offline$

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$Default$ Not sure what to do in this situation; Geometric Sequences

A2= -8
A7= 256
A12=?

Work thus far:
7-2=5
A7 = A2(r^5)
256/-8 = -8(r^5)
r^5=-32

I need the 5th root of -32...I know that the fifth root of 32=2, but what about that negative sign??

Thanks.

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#2

$Old$ October 27th, 2007, 03:33 PM

Plato $Plato is offline$

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$\sqrt[5]{{ - 32}} = - 2$

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#3

$Old$ October 27th, 2007, 03:42 PM

beetz $beetz is offline$

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AH. duuuuuuuuh. I put in -2, I thought, five times into the calculator but I looked back and saw I only put 4.

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