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:

I'm new to the forum and just started preparing. I have seen your quite a few replies and I'm impressed with your crisp logic. It's short and sweet. How did you learn? What books etc?

Thx

Hi HG,

To be frank, it is the active participation in the forum that has helped me learn the logic.

The OE says to start from subtracting equation 2 from equation 3. I started from adding all the equations in hope to reduce some variables later but came to nowhere. It was too difficult and time consuming for me to play with 3 equations until I got to the right solution. Please help me understand why exactly the 2nd from the 3rd and what logic should I follow when dealing with such problems?

I'm new to the forum and just started preparing. I have seen your quite a few replies and I'm impressed with your crisp logic. It's short and sweet. How did you learn? What books etc?

Didn't you like the Official Explanation for this question?

explanation is fine. My problem is that I wouldnt instinctively tackle the problem in that way. And the ways I did led me no where, even without a 2 minute time limit.

I think ill stick with the intelligent substitution idea.

The question is tough. x2suresh proposed a really nice alternative solution for it. While his approach won't necessarily work for all similar questions, it's very good for this one. Equation 2 was subtracted from equation 3 because further simplifications were possible after doing so.

Igor010 wrote:

The OE says to start from subtracting equation 2 from equation 3. I started from adding all the equations in hope to reduce some variables later but came to nowhere. It was too difficult and time consuming for me to play with 3 equations until I got to the right solution. Please help me understand why exactly the 2nd from the 3rd and what logic should I follow when dealing with such problems?

The question is tough. x2suresh proposed a really nice alternative solution for it. While his approach won't necessarily work for all similar questions, it's very good for this one. Equation 2 was subtracted from equation 3 because further simplifications were possible after doing so.

Igor010 wrote:

The OE says to start from subtracting equation 2 from equation 3. I started from adding all the equations in hope to reduce some variables later but came to nowhere. It was too difficult and time consuming for me to play with 3 equations until I got to the right solution. Please help me understand why exactly the 2nd from the 3rd and what logic should I follow when dealing with such problems?

I second this approach. Even I tried to add all the three equations and tried to figure out, but no use.

I found that except eq (1), rest are having addition of variables and Q!= R. So, I took P = R. Adding all the equations and using P=R and using some numbers, I hit on the C.

x2suresh wrote:

millhouse wrote:

If \(P^2 - QR = 10\) , \(Q^2 + PR = 10\) , \(R^2 + PQ = 10\) , and \(R \ne Q\) , what is the value of \(P^2 + Q^2 + R^2?\)

could someone please tell me how am i suppose to id the fastest way to solve this problem?

I totally support the number substitution method on this qtn. I attempted to do it through simplification, and it took almost 15 minutes to get to the answer. I'm guessing if I'm doing far too elaborate calculations, chances are there's a faster way of solving it within 2 mins, otherwise it wouldn't be on the GMAT.