Events & Promotions
|
|
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
Track
Your Progress
Practice
Pays
Not interested in getting valuable practice questions and articles delivered to your email? No problem, unsubscribe here.
May 2110:00 AM EDT
-11:59 PM EDT
Make the most of your break with the most realistic GMAT™ prep. Take up to $700 off select products.
May 2712:30 AM EDT
-01:30 AM EDT
At one point, she believed GMAT wasn’t for her. After scoring 595, self-doubt crept in and she questioned her potential. But instead of quitting, she made the right strategic changes. The result? A remarkable comeback to 695. Check out how Saakshi did it.
May 3012:30 AM EDT
-01:30 AM EDT
Struggling to find the right strategies to score a 99 %ile on GMAT Focus? Riya (GMAT 715) boosted her score by 100-points in just 15 days! Discover how the right mentorship, tailored strategies, and an unwavering mindset can transform your GMAT prep.
May 3102:00 PM PDT
-03:00 PM PDT
Video explanations + diagnosis of 10 weakest areas + 150+ short videos + study plan!
Jun 1006:00 AM PDT
-06:15 PM PDT
Register for the GMAT Club Virtual MBA Spotlight Fair – the world’s premier event for serious MBA candidates. This is your chance to hear directly from Admissions Directors at nearly every Top 30 MBA program..
16 Nov 2021, 09:45
Kudos
Bookmarks
D
Be sure to select an answer first to save it in the Error Log before revealing the correct answer (OA)!
Difficulty:
45%
(medium)
Question Stats:
69% (02:18) correct
31%
(02:40)
wrong
based on 354
sessions
History
Date
Time
Result
Not Attempted Yet
The expression \((\frac{1}{\sqrt{8 - \sqrt{63}}} +\frac{1}{\sqrt{8 +\sqrt{63}}})^2 =\)
(A) 21
(B) 20
(C) 19
(D) 18
(E) 17
(A) 21
(B) 20
(C) 19
(D) 18
(E) 17
16 Nov 2021, 10:08
Kudos
Bookmarks
Bunuel
Multiply by their conjugates to remove denominator.
\((\frac{1}{\sqrt{8 - \sqrt{63}}} +\frac{1}{\sqrt{8 +\sqrt{63}}})^2 =\)
\((\frac{ \sqrt{8 + \sqrt{63}}}{\sqrt{8 - \sqrt{63}}* \sqrt{8 + \sqrt{63}}} +\frac{ \sqrt{8 - \sqrt{63}}}{\sqrt{8 +\sqrt{63}}* \sqrt{8 - \sqrt{63}}})^2 =\)
\((\frac{ \sqrt{8 + \sqrt{63}}}{\sqrt{64 - {63}}} +\frac{ \sqrt{8 - \sqrt{63}}}{\sqrt{64 -{63}}})^2 =\)
\( (\sqrt{8 + \sqrt{63}}+\sqrt{8 - \sqrt{63}})^2\)
\( (\sqrt{8 + \sqrt{63}})^2+(\sqrt{8 - \sqrt{63}})^2\) \( +2(\sqrt{8 + \sqrt{63}}*\sqrt{8 - \sqrt{63}})\)
\(8+\sqrt{63}+8-\sqrt{63}+2=18\)
OR
\((\frac{1}{\sqrt{8 - \sqrt{63}}} +\frac{1}{\sqrt{8 +\sqrt{63}}})^2 =\)
\((\frac{ \sqrt{8 +\sqrt{63}}+ \sqrt{8 - \sqrt{63}}}{\sqrt{8 - \sqrt{63}}*\sqrt{8 +\sqrt{63}}})^2 =\)
\( (\sqrt{8 + \sqrt{63}}+\sqrt{8 - \sqrt{63}})^2\)
\( (\sqrt{8 + \sqrt{63}})^2+(\sqrt{8 - \sqrt{63}})^2\) \(+2 (\sqrt{8 + \sqrt{63}}*\sqrt{8 - \sqrt{63}})\)
\(8+\sqrt{63}+8-\sqrt{63}+2=18\)
Hi chetan2u, thank you for sharing your approach! I tried solving using identities as a first approach.
I then tried solving with your approach (multiplying by conjugate) and I am still getting it wrong. Can´t see where I commited the error
Any input would help inmensly!
Best regards
I then tried solving with your approach (multiplying by conjugate) and I am still getting it wrong. Can´t see where I commited the error
Any input would help inmensly!
Best regards
Attachments
IMG_3276.jpeg [ 2.38 MiB | Viewed 2682 times ]
