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

It is currently 17 Oct 2019, 09:06

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

(180^(1/2) +45^(1/2))/135^(1/2)

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

Hide Tags

Find Similar Topics 
Math Expert
User avatar
V
Joined: 02 Sep 2009
Posts: 58402
(180^(1/2) +45^(1/2))/135^(1/2)  [#permalink]

Show Tags

New post 25 Apr 2017, 03:08
00:00
A
B
C
D
E

Difficulty:

  35% (medium)

Question Stats:

72% (02:02) correct 28% (02:48) wrong based on 245 sessions

HideShow timer Statistics

GMAT Club Legend
GMAT Club Legend
User avatar
V
Joined: 12 Sep 2015
Posts: 4006
Location: Canada
Re: (180^(1/2) +45^(1/2))/135^(1/2)  [#permalink]

Show Tags

New post 25 Apr 2017, 06:26
2
Top Contributor
2
Bunuel wrote:
\(\frac{\sqrt{180}+\sqrt{45}}{\sqrt{135}}\)

A. \(\sqrt{3}\)

B. \(3\sqrt{3}\)

C. \(5\sqrt{3}\)

D. \(3\sqrt{5}\)

E. \(5\sqrt{5}\)


We'll simplify each root by using the rule: √(ab) = (√a)(√b)

√180 = √(36 x 5) = (√36)(√5) = 6√5
√45 = √(9 x 5) = (√9)(√5) = 3√5
√135 = √(9 x 15) = (√9)(√15) = 3√15

So, \(\frac{\sqrt{180}+\sqrt{45}}{\sqrt{135}}\) = (6√5 + 3√5)/(3√15)

= (9√5)/(3√15)
= 3/(√3)

Check the answer choices....not there!
We must rationalize the denominator.
Take 3/(√3) and multiply numerator and denominator by √3 to get: (3√3)/3, which simplifies to √3

Answer:

RELATED VIDEOS




_________________
Test confidently with gmatprepnow.com
Image
Intern
Intern
avatar
B
Joined: 01 Apr 2017
Posts: 2
Re: (180^(1/2) +45^(1/2))/135^(1/2)  [#permalink]

Show Tags

New post 25 Apr 2017, 06:33
Why not B. 3/sqrt 3 is in B

Sent from my XT1068 using GMAT Club Forum mobile app
GMAT Club Legend
GMAT Club Legend
User avatar
V
Joined: 12 Sep 2015
Posts: 4006
Location: Canada
Re: (180^(1/2) +45^(1/2))/135^(1/2)  [#permalink]

Show Tags

New post 25 Apr 2017, 06:42
Top Contributor
Somnath09 wrote:
Why not B. 3/sqrt 3 is in B

Sent from my XT1068 using GMAT Club Forum mobile app


Here's another way to think of it.
We know that (sqrt 3)(sqrt 3) = 3, so let's replace the numerator, 3, with (sqrt 3)(sqrt 3)

We get: 3/sqrt 3 = (sqrt 3)(sqrt 3)/(sqrt 3) =sqrt 3

Cheers,
Brent
_________________
Test confidently with gmatprepnow.com
Image
Manager
Manager
avatar
S
Joined: 05 Nov 2016
Posts: 83
GMAT ToolKit User
Re: (180^(1/2) +45^(1/2))/135^(1/2)  [#permalink]

Show Tags

New post 25 Apr 2017, 19:36
Taking \(\sqrt{45}\) common from numerator and denominator
\(\sqrt{45}\)(\(\sqrt{4}\)+1) / \(\sqrt{45}\)*(\(\sqrt{3}\))
(2+1)/\(\sqrt{3}\)
3/\(\sqrt{3}\)
\(\sqrt{3}\)
_________________
Kudos are always welcome ... as well your suggestions
Target Test Prep Representative
User avatar
G
Status: Head GMAT Instructor
Affiliations: Target Test Prep
Joined: 04 Mar 2011
Posts: 2816
Re: (180^(1/2) +45^(1/2))/135^(1/2)  [#permalink]

Show Tags

New post 28 Apr 2017, 15:15
1
1
Bunuel wrote:
\(\frac{\sqrt{180}+\sqrt{45}}{\sqrt{135}}\)

A. \(\sqrt{3}\)

B. \(3\sqrt{3}\)

C. \(5\sqrt{3}\)

D. \(3\sqrt{5}\)

E. \(5\sqrt{5}\)


We can start by simplifying √180, √45, and √135:

√180 = √36 x √5 = 6√5

√45 = √9 x √5 = 3√5

Thus, 6√5 + 3√5 = 9√5.

√135 = √9 x √15 = 3√15

We now have:

(9√5)/(3√15) = 3/√3

Finally, we rationalize the denominator, getting:

(3/√3)(√3/√3) = 3√3/3 = √3

Answer: A
_________________

Jeffrey Miller

Head of GMAT Instruction

Jeff@TargetTestPrep.com
TTP - Target Test Prep Logo
122 Reviews

5-star rated online GMAT quant
self study course

See why Target Test Prep is the top rated GMAT quant course on GMAT Club. Read Our Reviews

If you find one of my posts helpful, please take a moment to click on the "Kudos" button.

Non-Human User
User avatar
Joined: 09 Sep 2013
Posts: 13242
Re: (180^(1/2) +45^(1/2))/135^(1/2)  [#permalink]

Show Tags

New post 25 Mar 2019, 09:20
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 Club Bot
Re: (180^(1/2) +45^(1/2))/135^(1/2)   [#permalink] 25 Mar 2019, 09:20
Display posts from previous: Sort by

(180^(1/2) +45^(1/2))/135^(1/2)

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





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