Math questions and topics from the Official Guide and Quantitative Review books. Please try to follow the posting pattern (e.g. OG - DS - #142) to allow for easier searches. Questions posted in the GMAT Math section regarding the OG have been moved here.
CC
 
 

OG - PS - #40

by CC Wed Sep 12, 2007 4:43 pm

Which of the following cannot be a value of 1/x-1?

I don't get the explanation for this problem. The OG says "since 1 divided by any number can never equal zero".
if x=0 then the value would be 1/-1=-1.

Am I missing something?

thanks!
StaceyKoprince
ManhattanGMAT Staff
 
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by StaceyKoprince Mon Sep 17, 2007 7:58 pm

Please post the complete text of the problem, including answer choices. Please also make sure to use parentheses or other formatting when necessary - for instance, should this problem read 1/(x-1) or (1/x) - 1? Thanks!
Stacey Koprince
Instructor
Director, Content & Curriculum
ManhattanPrep
StaceyKoprince
ManhattanGMAT Staff
 
Posts: 9349
Joined: Wed Oct 19, 2005 9:05 am
Location: Montreal
 

by StaceyKoprince Mon Sep 17, 2007 8:01 pm

The OG says "since 1 divided by any number can never equal zero".
if x=0 then the value would be 1/-1=-1.


Please also clarify your question - the OG says the outcome of the division can't equal zero and the example you gave does not, in fact, equal zero. It equals -1. You set x=0, but the excerpt you quoted from OG does not say x can't equal zero.
Stacey Koprince
Instructor
Director, Content & Curriculum
ManhattanPrep