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:
From S1 we know that a·x^2+b=-a·x^2+d => x= +/- sqrt[(d-b)/(2·a)] We can not conclude anything because if b=d then the two paraboles cross in just one point so they do not really cross each other.
From S2 we can not conclude anything
From S1 & S2 we know that b and d are different and that x= +/- sqrt[(d-b)/(2·a)] , which means two different points, so they cross.
From S1 we know that a·x^2+b=-a·x^2+d => x= +/- sqrt[(d-b)/(2·a)] We can not conclude anything because if b=d then the two paraboles cross in just one point so they do not really cross each other.
From S2 we can not conclude anything
From S1 & S2 we know that b and d are different and that x= +/- sqrt[(d-b)/(2·a)] , which means two different points, so they cross.
Answer should be C.
(d-b)<0
a>0: (d-b)/(2·a)<0 ==> √((d-b)/(2·a)) is undefined. There are no roots. a<0: (d-b)/(2·a)>0 ==> √((d-b)/(2·a)) is defined. There are two roots. Insuff. _________________
From S1 we know that a·x^2+b=-a·x^2+d => x= +/- sqrt[(d-b)/(2·a)] We can not conclude anything because if b=d then the two paraboles cross in just one point so they do not really cross each other.
From S2 we can not conclude anything
From S1 & S2 we know that b and d are different and that x= +/- sqrt[(d-b)/(2·a)] , which means two different points, so they cross.
Answer should be C.
(d-b)<0
a>0: (d-b)/(2·a)<0 ==> √((d-b)/(2·a)) is undefined. There are no roots. a<0: (d-b)/(2·a)>0 ==> √((d-b)/(2·a)) is defined. There are two roots. Insuff.
Humm...tricky question. I think you are right. I got a bit confused not considering the sign of a. I considered a being either positive or negative. In such a case you can conclude that the paraboles either cross or not cross. You are right, E should be the answer.