Thank you for using the timer - this advanced tool can estimate your performance and suggest more practice questions. We have subscribed you to Daily Prep Questions via email.

Customized for You

we will pick new questions that match your level based on your Timer History

Track Your Progress

every week, we’ll send you an estimated GMAT score based on your performance

Practice Pays

we will pick new questions that match your level based on your Timer History

Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.

It appears that you are browsing the GMAT Club forum unregistered!

Signing up is free, quick, and confidential.
Join other 500,000 members and get the full benefits of GMAT Club

Registration gives you:

Tests

Take 11 tests and quizzes from GMAT Club and leading GMAT prep companies such as Manhattan GMAT,
Knewton, and others. All are free for GMAT Club members.

Applicant Stats

View detailed applicant stats such as GPA, GMAT score, work experience, location, application
status, and more

Books/Downloads

Download thousands of study notes,
question collections, GMAT Club’s
Grammar and Math books.
All are free!

Thank you for using the timer!
We noticed you are actually not timing your practice. Click the START button first next time you use the timer.
There are many benefits to timing your practice, including:

For any numbers a and b, ab= a + b - ab. If ab=0, which of the following CANNOT be a value of b?

A. 2 B. 1 C. 0 D. -1 E. -3/2

Some function (#) is defined for all numbers \(a\) and \(b\) as \(a#b= a + b - ab\).

Now, since given that \(a#b=0\), then \(a + b - ab=0\) --> \(a=\frac{b}{b-1}\) --> if \(b=1\) then the given expression is undefined so \(b\) cannot equal to 1.

Or: \(a + b - ab=0\) --> \((a-1)(1-b)+1=0\) --> \((a-1)(1-b)=-1\). If \(b=1\), then \((a-1)(1-b)=0\) not -1, so \(b\) cannot equal to 1.

Re: For any numbers a and b, ab= a + b - ab. If ab=0, which of [#permalink]

Show Tags

06 Jul 2012, 00:55

Can someone pls edit the question.? i was wondering where i was going wrong thinking. question was ab=a+b-ab => 2ab=a+b. and then saw bunuel's reply then understood what the question was!
_________________

Re: For any numbers a and b, ab= a + b - ab. If ab=0, which of [#permalink]

Show Tags

25 Jul 2012, 01:40

asax wrote:

Can someone pls edit the question.? i was wondering where i was going wrong thinking. question was ab=a+b-ab => 2ab=a+b. and then saw bunuel's reply then understood what the question was!

Even I got it wrong...
_________________

I've failed over and over and over again in my life and that is why I succeed--Michael Jordan Kudos drives a person to better himself every single time. So Pls give it generously Wont give up till i hit a 700+

Re: For any numbers a and b, ab= a + b - ab. If ab=0, which of [#permalink]

Show Tags

11 Apr 2013, 04:59

asax wrote:

Can someone pls edit the question.? i was wondering where i was going wrong thinking. question was ab=a+b-ab => 2ab=a+b. and then saw bunuel's reply then understood what the question was!

Can someone pls edit the question.? i was wondering where i was going wrong thinking. question was ab=a+b-ab => 2ab=a+b. and then saw bunuel's reply then understood what the question was!

Re: For any numbers a and b, a#b=a + b - ab. If a#b=0, which of [#permalink]

Show Tags

11 Apr 2013, 05:15

Stiv wrote:

For any numbers a and b, a#b=a + b - ab. If a#b=0, which of the following CANNOT be a value of b?

A. 2 B. 1 C. 0 D. -1 E. -3/2

------------------------------------------ for me the fastest way must be the use of answer choices to find the value of a if a will be an integer after putting the value of of b as given in the answer choices then the answer will be correct with no cumbersome calculations & its fast too ....!! _________________

If you don’t make mistakes, you’re not working hard. And Now that’s a Huge mistake.

Re: For any numbers a and b, a#b=a + b - ab. If a#b=0, which of [#permalink]

Show Tags

16 Jul 2014, 21:40

Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________

There’s something in Pacific North West that you cannot find anywhere else. The atmosphere and scenic nature are next to none, with mountains on one side and ocean on...

This month I got selected by Stanford GSB to be included in “Best & Brightest, Class of 2017” by Poets & Quants. Besides feeling honored for being part of...

Joe Navarro is an ex FBI agent who was a founding member of the FBI’s Behavioural Analysis Program. He was a body language expert who he used his ability to successfully...