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100 points for $49 worth of Veritas practice GMATs FREE VERITAS PRACTICE GMAT EXAMS Earn 10 Points Per Post Earn 10 Points Per Thanks Earn 10 Points Per Upvote ## For any numbers a and b, a#b=a + b - ab. If a#b=0, which of tagged by: M7MBA ##### This topic has 1 expert reply and 1 member reply ## For any numbers a and b, a#b=a + b - ab. If a#b=0, which of 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 The OA is the option B. Experts, how can I get an answer here? Should I try option by option? Could you give me some help, please? Thanks in advanced. ### GMAT/MBA Expert GMAT Instructor Joined 25 Apr 2015 Posted: 1776 messages Followed by: 14 members Upvotes: 43 Top Reply M7MBA 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 We are given that a#b=a + b - ab and that a#b=0. Thus we have a + b - ab = 0 a + b = ab Now letâ€™s look at the choices: A. If b = 2, then a + 2 = a(2) 2 = a So b can be 2. B. If b = 1, then a + 1 = a(1) We see that a + 1 (1 more than a) canâ€™t be equal to a itself. So b CANNOT be 1, and that is the number we are looking for. Alternate Solution: We are given that a#b=a + b - ab and that a#b=0. Thus we have a + b - ab = 0 a + b = ab b = ab - a b = a(b - 1) We observe here that for any value of b other than 1, we can divide each side of the equality by b - 1 and express a as b/(b - 1). Thus, the only value that b cannot assume is 1. Answer: B _________________ Scott Woodbury-Stewart Founder and CEO Master | Next Rank: 500 Posts Joined 15 Oct 2009 Posted: 320 messages Upvotes: 27 M7MBA 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 The OA is the option B. Experts, how can I get an answer here? Should I try option by option? Could you give me some help, please? Thanks in advanced. a#b= 0 means that a +b -ab = 0 also. Which means that a+b=ab Test the answers. Can b=2 ? Substitute 2 for b a+2=2a works if a=2 so yes it's possible Can b=1 ? a+1=a > only possible if 1=0, which isn't true, therefore 1, B • Get 300+ Practice Questions 25 Video lessons and 6 Webinars for FREE Available with Beat the GMAT members only code • Magoosh Study with Magoosh GMAT prep Available with Beat the GMAT members only code • 5-Day Free Trial 5-day free, full-access trial TTP Quant Available with Beat the GMAT members only code • 5 Day FREE Trial Study Smarter, Not Harder Available with Beat the GMAT members only code • Free Trial & Practice Exam BEAT THE GMAT EXCLUSIVE Available with Beat the GMAT members only code • Free Veritas GMAT Class Experience Lesson 1 Live Free Available with Beat the GMAT members only code • 1 Hour Free BEAT THE GMAT EXCLUSIVE Available with Beat the GMAT members only code • FREE GMAT Exam Know how you'd score today for$0

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