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DEFINED OPERATIONS

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DEFINED OPERATIONS

by centermass1976 » Thu Oct 02, 2008 11:46 am
Hi everybody--great site. I have trouble performing, even understanding, defined operation problems. What's more, there doesn't seem to be many examples on this site of such problems. Here's an example:

If x ? y= x/y(y-x), then 1/3 ? (4/3 ? 2/3)= what


I have the answere, but I am having a hard time following it past the first paranthesis (which is -4/3). After that, it doen't make any sense. I'm sure the logic is quite easy and I would hate to miss a question like this on the exam (less than a week!)--Thanks--Clint
--The question may be viewed at: https://www.west.net/~stewart/gmat/ps_smpl.htm
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by Morgoth » Thu Oct 02, 2008 12:02 pm
x ? y= x/y(y-x), then 1/3 ? (4/3 ? 2/3)

lets solve

(4/3 ? 2/3) = 4/3 / 2/3 [2/3-4/3] = 4/2 [-2/3] = -4/3

1/3 ? -4/3 = 1/3 / -4/3 [-4/3 - 1/3] = -1/4 [-5/3] = 5/12

Hope this helps.
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