GMAT Club Forumhttps://gmatclub.com:443/forum/ For integers a and b, is the expression ab – b even?https://gmatclub.com/forum/for-integers-a-and-b-is-the-expression-ab-b-even-242106.html Page 1 of 1

 Author: Bunuel [ 06 Jun 2017, 11:42 ] Post subject: For integers a and b, is the expression ab – b even? For integers a and b, is the expression ab – b even?(1) a is odd(2) b is odd

 Author: BrentGMATPrepNow [ 06 Jun 2017, 11:55 ] Post subject: Re: For integers a and b, is the expression ab – b even? Bunuel wrote:For integers a and b, is the expression ab – b even?(1) a is odd(2) b is oddTarget question: Is the expression ab – b even?HINT: notice that ab – b = b(a - 1) Statement 1: a is odd What does does this tell us about the expression ab – b?Well, ab – b = b(a - 1)= b(ODD - 1)= b(EVEN) [since an odd integer minus 1 gives us a EVEN integer]= EVENSince we can answer the target question with certainty, statement 1 is SUFFICIENT Statement 2: b is odd There are several values of a and b that satisfy statement 2. Here are two: Case a: a = 3 and b = 1. In this case ab – b = (3)(1) - 1 = 2. So, ab – b is EVENCase b: a = 2 and b = 1. In this case ab – b = (2)(1) - 1 = 1. So, ab – b is ODDSince we cannot answer the target question with certainty, statement 2 is NOT SUFFICIENTAnswer: Cheers,Brent

 Author: Gnpth [ 25 Jul 2017, 17:49 ] Post subject: Re: For integers a and b, is the expression ab – b even? ab-b can be converted into b(a-1), We have to find either b or a-1 to be even. st-1 says a is odd. then a-1 is even. So the term b(a-1) will be even. sufficient.st-2 says b is odd. No info about a. so not sufficient. Answer is A.

 Author: ocelot22 [ 16 Jan 2019, 13:20 ] Post subject: Re: For integers a and b, is the expression ab – b even? Bunuel wrote:For integers a and b, is the expression ab – b even?(1) a is odd(2) b is oddb(a-1) even?(1) a odd, then a-1 is even, then we have even *b = even sufficient(2) b odd. Let be =1 1(a-1) even? let a=1. Then ab-b = 1(0) = 0 Yes even. Let a=2 then ab-b 1(2-1) =1 No. Odd. NSAnswer is A

 Author: bumpbot [ 20 Dec 2022, 08:08 ] Post subject: Re: For integers a and b, is the expression ab b even? 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.

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