It is currently 22 Feb 2018, 02:44

Close

GMAT Club Daily Prep

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.

Close

Request Expert Reply

Confirm Cancel

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

If a > b > 0, then √a^2 - b^2

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  
Author Message
TAGS:

Hide Tags

Intern
Intern
avatar
Joined: 21 Dec 2014
Posts: 14
If a > b > 0, then √a^2 - b^2 [#permalink]

Show Tags

New post 08 May 2015, 04:07
6
This post was
BOOKMARKED
00:00
A
B
C
D
E

Difficulty:

  5% (low)

Question Stats:

84% (00:30) correct 16% (00:54) wrong based on 208 sessions

HideShow timer Statistics

If a > b > 0, then \(\sqrt{a^2 - b^2}\)

A. \(a + b - \sqrt{2ab}\)
B. \(a - b + \sqrt{2ab}\)
C. \(\sqrt{(a-b)^2 - 2ab}\)
D. \((\sqrt{a+b}) (\sqrt{a-b})\)
E. \((\sqrt{a} + \sqrt{b}) (\sqrt{a}-\sqrt{b})\)



What is the difference between D and E

I thought because of the numbers being all under the square root e.g. in D \((\sqrt{a+b})\)
that you will have to subtract a from b first giving e.g. answer\(\sqrt{c}\) and for the other one e.g.\(\sqrt{d}\)

And therefore \((\sqrt{c})(\sqrt{d})\) a totally different value?
[Reveal] Spoiler: OA

Last edited by Bunuel on 08 May 2015, 04:25, edited 1 time in total.
Edited the question.
Expert Post
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 43862
Re: If a > b > 0, then √a^2 - b^2 [#permalink]

Show Tags

New post 08 May 2015, 04:29
Expert's post
3
This post was
BOOKMARKED
Jeli13 wrote:
If a > b > 0, then \(\sqrt{a^2 - b^2}\)

A. \(a + b - \sqrt{2ab}\)
B. \(a - b + \sqrt{2ab}\)
C. \(\sqrt{(a-b)^2 - 2ab}\)
D. \((\sqrt{a+b}) (\sqrt{a-b})\)
E. \((\sqrt{a} + \sqrt{b}) (\sqrt{a}-\sqrt{b})\)



What is the difference between D and E

I thought because of the numbers being all under the square root e.g. in D \((\sqrt{a+b})\)
that you will have to subtract a from b first giving e.g. answer\(\sqrt{c}\) and for the other one e.g.\(\sqrt{d}\)

And therefore \((\sqrt{c})(\sqrt{d})\) a totally different value?


\(a^2 - b^2 = (a + b)(a - b)\), thus \(\sqrt{a^2 - b^2}=\sqrt{(a + b)(a - b)}\), which is the same as \(\sqrt{(a + b)}\sqrt{(a - b)}\).

Answer: D.
_________________

New to the Math Forum?
Please read this: Ultimate GMAT Quantitative Megathread | All You Need for Quant | PLEASE READ AND FOLLOW: 12 Rules for Posting!!!

Resources:
GMAT Math Book | Triangles | Polygons | Coordinate Geometry | Factorials | Circles | Number Theory | Remainders; 8. Overlapping Sets | PDF of Math Book; 10. Remainders | GMAT Prep Software Analysis | SEVEN SAMURAI OF 2012 (BEST DISCUSSIONS) | Tricky questions from previous years.

Collection of Questions:
PS: 1. Tough and Tricky questions; 2. Hard questions; 3. Hard questions part 2; 4. Standard deviation; 5. Tough Problem Solving Questions With Solutions; 6. Probability and Combinations Questions With Solutions; 7 Tough and tricky exponents and roots questions; 8 12 Easy Pieces (or not?); 9 Bakers' Dozen; 10 Algebra set. ,11 Mixed Questions, 12 Fresh Meat

DS: 1. DS tough questions; 2. DS tough questions part 2; 3. DS tough questions part 3; 4. DS Standard deviation; 5. Inequalities; 6. 700+ GMAT Data Sufficiency Questions With Explanations; 7 Tough and tricky exponents and roots questions; 8 The Discreet Charm of the DS; 9 Devil's Dozen!!!; 10 Number Properties set., 11 New DS set.


What are GMAT Club Tests?
Extra-hard Quant Tests with Brilliant Analytics

Intern
Intern
avatar
Joined: 21 Dec 2014
Posts: 14
Re: If a > b > 0, then √a^2 - b^2 [#permalink]

Show Tags

New post 08 May 2015, 04:48
mmhh ok seem to have overcomplicated my thoughts
Intern
Intern
User avatar
Joined: 08 Sep 2014
Posts: 25
GMAT Date: 07-11-2015
GPA: 2.9
WE: Account Management (Computer Software)
If a > b > 0, then √a^2 - b^2 [#permalink]

Show Tags

New post 21 May 2015, 03:50
I picked numbers for this question, a = 2 and b = 1 yields \(\sqrt{3}\) and the only answer choice that yields \(\sqrt{3}\) when substituting a for 2 and b for 1 is D.
Non-Human User
User avatar
Joined: 09 Sep 2013
Posts: 13800
Premium Member
Re: If a > b > 0, then √a^2 - b^2 [#permalink]

Show Tags

New post 25 Jan 2018, 18:43
Hello from the GMAT Club BumpBot!

Thanks to another GMAT Club member, I have just discovered this valuable topic, yet it had no discussion for over a year. I am now bumping it up - doing my job. I think you may find it valuable (esp those replies with Kudos).

Want to see all other topics I dig out? Follow me (click follow button on profile). You will receive a summary of all topics I bump in your profile area as well as via email.
_________________

GMAT Books | GMAT Club Tests | Best Prices on GMAT Courses | GMAT Mobile App | Math Resources | Verbal Resources

Re: If a > b > 0, then √a^2 - b^2   [#permalink] 25 Jan 2018, 18:43
Display posts from previous: Sort by

If a > b > 0, then √a^2 - b^2

  new topic post reply Question banks Downloads My Bookmarks Reviews Important topics  


GMAT Club MBA Forum Home| About| Terms and Conditions| GMAT Club Rules| Contact| Sitemap

Powered by phpBB © phpBB Group | Emoji artwork provided by EmojiOne

Kindly note that the GMAT® test is a registered trademark of the Graduate Management Admission Council®, and this site has neither been reviewed nor endorsed by GMAC®.