GMAT Question of the Day: Daily via email | Daily via Instagram New to GMAT Club? Watch this Video

 It is currently 08 Apr 2020, 21:39

### 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

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

# [(5√3+3√5)/(√5+√3)]^2=?

Author Message
TAGS:

### Hide Tags

Math Revolution GMAT Instructor
Joined: 16 Aug 2015
Posts: 8787
GMAT 1: 760 Q51 V42
GPA: 3.82

### Show Tags

Updated on: 24 Nov 2016, 21:26
00:00

Difficulty:

35% (medium)

Question Stats:

75% (01:58) correct 25% (02:23) wrong based on 75 sessions

### HideShow timer Statistics

$$[(5√3+3√5)/(√5+√3)]^2$$=?

A. √6
B. √15
C. 15
D. √24
E. 6

_________________
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 $79 for 1 month Online Course" "Free Resources-30 day online access & Diagnostic Test" "Unlimited Access to over 120 free video lessons - try it yourself" Originally posted by MathRevolution on 28 Sep 2016, 03:01. Last edited by MathRevolution on 24 Nov 2016, 21:26, edited 3 times in total. Math Expert Joined: 02 Aug 2009 Posts: 8321 Re: [(5√3+3√5)/(√5+√3)]^2=? [#permalink] ### Show Tags 28 Sep 2016, 03:24 MathRevolution wrote: [(5√3+3√5)/(√5+√3)]2=? A. √6 B. √15 C. 15 D. √24 E. 6 (5√3+3√5)/(√5+√3)]2=[(√5*√5*√3+√3*√3*√5)/(√5+√3)]*2= [(√5+√3)(√5*√3)/(√5+√3)]*2=2√15.. But looking at the answer, it seems it is not *2 but ^2.. So answer = (√15)^2=15.. C.. Request Mathrevolution, pl post Q correctly. Most of the time one has to work reverse.. Look at the OA and then correct Q accordingly _________________ Manager Joined: 29 Aug 2008 Posts: 101 Re: [(5√3+3√5)/(√5+√3)]^2=? [#permalink] ### Show Tags 28 Sep 2016, 03:47 chetan2u wrote: MathRevolution wrote: [(5√3+3√5)/(√5+√3)]2=? A. √6 B. √15 C. 15 D. √24 E. 6 (5√3+3√5)/(√5+√3)]2=[(√5*√5*√3+√3*√3*√5)/(√5+√3)]*2= [(√5+√3)(√5*√3)/(√5+√3)]*2=2√15.. But looking at the answer, it seems it is not *2 but ^2.. So answer = (√15)^2=15.. C.. Request Mathrevolution, pl post Q correctly. Most of the time one has to work reverse.. Look at the OA and then correct Q accordingly Exactly, did same calculation and got 2√15. But based on that square at top the answer would be option C. GMAT Club Legend Joined: 11 Sep 2015 Posts: 4604 Location: Canada GMAT 1: 770 Q49 V46 Re: [(5√3+3√5)/(√5+√3)]^2=? [#permalink] ### Show Tags 28 Sep 2016, 06:57 3 Top Contributor MathRevolution wrote: [(5√3+3√5)/(√5+√3)]²=? A. √6 B. √15 C. 15 D. √24 E. 6 [(5√3+3√5)/(√5+√3) Square numerator and denominator to get: [75 + 15√15 + 15√15 + 45]/[5 + √15 + √15 + 3] Simplify to get: [120 + 30√15]/[8 + 2√15] NOTE: At this point, we COULD multiply top and bottom by the conjugate (8 - 2√15). HOWEVER, we can save time by recognizing that we can first factor the top and bottom. Factor the top and bottom to get: [30(4 + √15)]/[2(4 + √15)] Eliminate (4 + √15) from top and bottom to get: 30/2 Evaluate: 15 Answer: RELATED VIDEOS _________________ Test confidently with gmatprepnow.com Math Revolution GMAT Instructor Joined: 16 Aug 2015 Posts: 8787 GMAT 1: 760 Q51 V42 GPA: 3.82 Re: [(5√3+3√5)/(√5+√3)]^2=? [#permalink] ### Show Tags 30 Sep 2016, 06:44 ==> [(5√3+3√5)/(√5+√3)]2=[√15(√5+√3)/(√5+√3)]2=(√15)2=15 Hence the answer is C. Answer: C _________________ 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$79 for 1 month Online Course"
"Free Resources-30 day online access & Diagnostic Test"
"Unlimited Access to over 120 free video lessons - try it yourself"
Senior Manager
Joined: 12 Dec 2015
Posts: 473

### Show Tags

22 Feb 2020, 08:51
$$[(5√3+3√5)/(√5+√3)]^2$$=?

A. √6
B. √15
C. 15 --> correct: $$[(5√3+3√5)/(√5+√3)]^2= [(√5√3)(√5+√3)/(√5+√3)]^2 = (√5√3)^2 = 15$$
D. √24
E. 6
Re: [(5√3+3√5)/(√5+√3)]^2=?   [#permalink] 22 Feb 2020, 08:51
Display posts from previous: Sort by