variables

Expert replies

naaga: Master | Next Rank: 500 Posts; Posts: 129; Joined: Mon Dec 15, 2008 11:43 pm; Location: Hyderabad; Thanked: 2 times

by naaga » Mon Feb 16, 2009 5:18 am

17. If x≠0 and x= sqrt 4xy- 4y^2 then, in terms of y, x=
(A) 2y

(B) y

(C) y/2

(D) (-4y^2)/(1-2y)

(E) –2y

folks help me out ...
thanks in advance

Like this post

Source: Beat The GMAT — Problem Solving | Mon Feb 16, 2009 5:18 am

DanaJ: Site Admin; Posts: 2567; Joined: Thu Jan 01, 2009 10:05 amFollowed by: 550 members; Thanked: 712 times; GMAT Score:770

by DanaJ » Mon Feb 16, 2009 6:08 am

I'm going to assume that you mean x = sqrt(4xy - 4y^2). Raise to the second power and you get that:
x^2 = 4xy - 4y^2. Now "send" everything to the left and you get:
x^2 - 4xy + 4y^2 = 0. This one is equivalent to (x - 2y)^2 = 0 or that x - 2y = 0. This makes x = 2y with answer A.

Like this post

Post new topic Post Reply

• Page 1 of 1

GMAT Course Reviews

560 reviews

1168 reviews

431 reviews

359 reviews

147 reviews

5/5

5 Star (560 Reviews)

"Target Test Prep is the closest to the official version of the GMAT exam, about 99% accuracy in terms of the quality and quantity of information. The course has excellently created singular sets of focused lessons and tests for every possible topic that one could come across in the official GMAT exam."

"The TTP course maximizes the efficiency of the time you spend studying. It will take time and effort but I could almost guarantee that if you complete the course exactly as it is laid out you will get an amazing score. They also have a very responsive team willing to help with any questions you might have."

"TTP has two things that I think no other test prep company offers: A teaching approach that reinforces understanding and an attitude that will give you the mental preparedness needed to succeed on the test. TTP gives you a deep understanding of the concept you need to know while teaching you how to think."

Write a Review