GMAT Question of the Day - Daily to your Mailbox; hard ones only

It is currently 17 Nov 2018, 01:20

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 in November
PrevNext
SuMoTuWeThFrSa
28293031123
45678910
11121314151617
18192021222324
2526272829301
Open Detailed Calendar
  • FREE Quant Workshop by e-GMAT!

     November 18, 2018

     November 18, 2018

     07:00 AM PST

     09:00 AM PST

    Get personalized insights on how to achieve your Target Quant Score. November 18th, 7 AM PST
  • How to QUICKLY Solve GMAT Questions - GMAT Club Chat

     November 20, 2018

     November 20, 2018

     09:00 AM PST

     10:00 AM PST

    The reward for signing up with the registration form and attending the chat is: 6 free examPAL quizzes to practice your new skills after the chat.

(1+√3+√5)^2-(√3+√5)^2=?

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

Hide Tags

Math Revolution GMAT Instructor
User avatar
V
Joined: 16 Aug 2015
Posts: 6517
GMAT 1: 760 Q51 V42
GPA: 3.82
Premium Member
(1+√3+√5)^2-(√3+√5)^2=?  [#permalink]

Show Tags

New post 26 Jun 2016, 06:38
00:00
A
B
C
D
E

Difficulty:

  25% (medium)

Question Stats:

80% (01:26) correct 20% (01:48) wrong based on 178 sessions

HideShow timer Statistics

(1+√3+√5)^2-(√3+√5)^2=?
A. 1+2√3+2√5
B. 1+2√3+3√5
C. 1-√3+√5
D. 1+√3-√5
E. √3+√5

*An answer will be posted in 2 days.

_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
"Only $99 for 3 month Online Course"
"Free Resources-30 day online access & Diagnostic Test"
"Unlimited Access to over 120 free video lessons - try it yourself"

Current Student
User avatar
Joined: 18 Oct 2014
Posts: 855
Location: United States
GMAT 1: 660 Q49 V31
GPA: 3.98
GMAT ToolKit User
Re: (1+√3+√5)^2-(√3+√5)^2=?  [#permalink]

Show Tags

New post 26 Jun 2016, 07:27
3
(1+√3+√5)^2-(√3+√5)^2

(1+√3)^2 + 5 +2 (1+√3) (√5) - ( 3 +5 + 2√3√5)

1+ 3+ 2√3 +5 +2 √5 + 2 √15 - 3-5 -2√15

1+2√3+2√5

A is the answer
_________________

I welcome critical analysis of my post!! That will help me reach 700+

CEO
CEO
User avatar
D
Joined: 11 Sep 2015
Posts: 3122
Location: Canada
(1+√3+√5)^2-(√3+√5)^2=?  [#permalink]

Show Tags

New post Updated on: 16 Oct 2018, 06:54
3
Top Contributor
1
(1+√3+√5)² - (√3+√5)² = ?

A. 1+2√3+2√5
B. 1+2√3+3√5
C. 1-√3+√5
D. 1+√3-√5
E. √3+√5



Nice question!
First recognize that (1+√3+√5)² - (√3+√5)² is a DIFFERENCE OF SQUARES.
Here are some examples of differences of squares:
x² - 25y²
4x² - 9y²
49m² - 100k²

In general, we can factor differences of squares as follows:
- = (a+b)(a-b)

So, (1+√3+√5)² - (√3+√5)² = [(1+√3+√5) + (√3+√5)][(1+√3+√5) - (√3+√5)]
= [1+2√3+2√5][1]
= 1+2√3+2√5

Answer:
_________________

Test confidently with gmatprepnow.com
Image


Originally posted by GMATPrepNow on 26 Jun 2016, 11:42.
Last edited by GMATPrepNow on 16 Oct 2018, 06:54, edited 1 time in total.
Math Revolution GMAT Instructor
User avatar
V
Joined: 16 Aug 2015
Posts: 6517
GMAT 1: 760 Q51 V42
GPA: 3.82
Premium Member
Re: (1+√3+√5)^2-(√3+√5)^2=?  [#permalink]

Show Tags

New post 27 Jun 2016, 17:30
A^2-B^2=(A+B)(A-B). Hence, the correct answer is A.
_________________

MathRevolution: Finish GMAT Quant Section with 10 minutes to spare
The one-and-only World’s First Variable Approach for DS and IVY Approach for PS with ease, speed and accuracy.
"Only $99 for 3 month Online Course"
"Free Resources-30 day online access & Diagnostic Test"
"Unlimited Access to over 120 free video lessons - try it yourself"

Manager
Manager
User avatar
B
Joined: 01 Jan 2016
Posts: 54
GPA: 3.75
WE: Engineering (Energy and Utilities)
Re: (1+√3+√5)^2-(√3+√5)^2=?  [#permalink]

Show Tags

New post 20 Aug 2017, 04:09
MathRevolution wrote:
(1+√3+√5)^2-(√3+√5)^2=?
A. 1+2√3+2√5
B. 1+2√3+3√5
C. 1-√3+√5
D. 1+√3-√5
E. √3+√5

*An answer will be posted in 2 days.


you can even do it with (A+B)^2 formula:

let √3+√5=x
Then the question becomes:
(1+x)^2-(x)^2=1^2+x^2+2x-x^2=1+2x=1+2(√3+√5)= option B
_________________


If you like it, give kudos. Thanks :)


The price of success is hard work, dedication to the job at hand, and the determination that whether we win or lose, we have applied the best of ourselves to the task at hand.
~Vince Lombardi

CEO
CEO
User avatar
D
Joined: 11 Sep 2015
Posts: 3122
Location: Canada
Re: (1+√3+√5)^2-(√3+√5)^2=?  [#permalink]

Show Tags

New post 20 Aug 2017, 05:27
Top Contributor
MathRevolution wrote:
(1+√3+√5)^2 - (√3+√5)^2=?
A. 1+2√3+2√5
B. 1+2√3+3√5
C. 1-√3+√5
D. 1+√3-√5
E. √3+√5


Another approach:

For test day, everyone should know the following approximations:
√2 ≈ 1.4
√3 ≈ 1.7
√5 ≈ 2.2


So, (1+√3+√5)² - (√3+√5)² ≈ (1+ 1.7 + 2.2)² - (1.7 + 2.2)²
≈ (4.9)² - (3.9)²
≈ 25 - 16
9

Now check the answer choices....
A. 1+2√3+2√5 ≈ 1 + 2(1.7) + 2(2.2) ≈ 8.8. CLOSE - KEEP
B. 1+2√3+3√5 ≈ 1 + 2(1.7) + 3(2.2) ≈ 11. ELIMINATE
C. 1-√3+√5 ≈ 1 - 1.7 + 2.2 ≈ 1.5. ELIMINATE
D. 1+√3-√5 ≈1 + 1.7 - 2.2 ≈ 0.4. ELIMINATE
E. √3+√5 ≈ 1.7 + 2.2 ≈ 3.9. ELIMINATE

Answer:
_________________

Test confidently with gmatprepnow.com
Image

Non-Human User
User avatar
Joined: 09 Sep 2013
Posts: 8794
Premium Member
Re: (1+√3+√5)^2-(√3+√5)^2=?  [#permalink]

Show Tags

New post 23 Oct 2018, 23:25
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

GMAT Club Bot
Re: (1+√3+√5)^2-(√3+√5)^2=? &nbs [#permalink] 23 Oct 2018, 23:25
Display posts from previous: Sort by

(1+√3+√5)^2-(√3+√5)^2=?

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


Copyright

GMAT Club MBA Forum Home| About| Terms and Conditions and Privacy Policy| 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®.