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.

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:

It is clear that statement (2) by itself is sufficient.
What about statement (1)?
It is possible to know X and Y if you have the values of XY and X-Y. Let's take C=-A.
We have AC=-40 and A+C=18
A and C are solutions of XÂ²-(A+C)X+AC=0, ie, XÂ²+40X+18=0. Thus, we can obtain A and C, A and B and calculate AB(A+2B).
What is the problem with this since the correct solution is B???

It is clear that statement (2) by itself is sufficient. What about statement (1)? It is possible to know X and Y if you have the values of XY and X-Y. Let's take C=-A. We have AC=-40 and A+C=18 A and C are solutions of XÂ²-(A+C)X+AC=0, ie, XÂ²+40X+18=0. Thus, we can obtain A and C, A and B and calculate AB(A+2B). What is the problem with this since the correct solution is B???

PS: Following my point of view, the answer is C

if you've already written that statement 2 by itself is sufficient, then you have to choose B. B always over-rides C.

Alex_NL wrote:

A = 2 or -2 B = 20

Which will give different solutions

Combined statements will say A = 2 and B = 20

Correct me if I am wrong.

A could be 2 or -2, but only 2 will work with 20 to make 80, so it has to be the positive version.

This is a great question because it exemplifies a common trick ont he GMAT. They want us to pick D. The question starts out with an equation with two variables, and if we've got two variables, then another equation should be enough to solve the problem.

But be weary of that. Always double check. When variables multiply by themselves, they square, and that often leads to 2 solutions and not enough information. In the first statement, that's what happens. If you solve for B, you get that it could be either 20 or -2. That means A could be either -20 or 2, and both solutions work in both equations. So not enough information.

2 let's us know that A^2B is 80. Since we already knew that AB is 40, the extra A must be a positive 2, so be must be a positive 20, and that's sufficient.

If you are looking for me to comment on your method for solving 1, I'm not sure I understand it. I think you've made it too difficult. Don't try to look for sophisticated solutions on most problems. The GMAT won't ask you to do the kind of thing you did. If you're already comfortable with substitution to the point where you're changing variables around, then just do the substitution and see logically if it makes sense that there could be two different answers. If yes, then there's not enough information to solve the problem.

It’s been a long time, since I posted. A busy schedule at office and the GMAT preparation, fully tied up with all my free hours. Anyways, now I’m back...

Ah yes. Funemployment. The time between when you quit your job and when you start your MBA. The promised land that many MBA applicants seek. The break that every...

It is that time of year again – time for Clear Admit’s annual Best of Blogging voting. Dating way back to the 2004-2005 application season, the Best of Blogging...