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

It is currently 20 May 2019, 17:45

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

Which of the following equations has 1 + √2 as one of its roots?

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

Hide Tags

 
Manager
Manager
avatar
B
Joined: 08 Sep 2016
Posts: 113
Re: Which of the following equations has 1 + √2 as one of its roots?  [#permalink]

Show Tags

New post 03 May 2018, 16:56
I found estimation to work the best.
Sqrt2= 1.4
1+sqrt2 = 2.4
One root = 2.4 or x =2.4
X^2 = 5.76
2x= 4.8

Now you have all the values to solve. You are trying to see which expression will give you the closest value to zero.

C can be immediately crossed off because you are adding throughout the expression

When you subtract 5.76 - 4.8, you get a value close to 1 being left over.

Equation D matches what you are looking for.
Manager
Manager
avatar
S
Joined: 10 Apr 2018
Posts: 129
Concentration: Leadership, Operations
GMAT 1: 600 Q44 V28
GPA: 3.56
WE: Engineering (Computer Software)
Reviews Badge
Re: Which of the following equations has 1 + √2 as one of its roots?  [#permalink]

Show Tags

New post 22 Aug 2018, 01:48
1
fla wrote:
Bunuel wrote:
Which of the following equations has 1 + √2 as one of its roots?

A) x^2 + 2x – 1 = 0
B) x^2 – 2x + 1 = 0
C) x^2 + 2x + 1 = 0
D) x^2 – 2x – 1 = 0
E) x^2 – x – 1= 0


If x1 = 1 + √2 then x2 = 1 - √2.

By the Viete theorem:
b = -(x1 + x2) = -(1 + √2 + 1 - √2) = -2
c = x1 * x2 = (1 + √2)(1 - √2) = 1 - 2 = -1
is the answer.


This is one of the simplest methods. Thanks.
_________________


The Graceful
----------------------------------------------------------
Every EXPERT was a beginner once...
Don't look at the clock. Do what it does, keep going
..
To achieve great things, two things are needed:a plan and not quite enough time - Leonard Bernstein.
Intern
Intern
avatar
Joined: 06 May 2018
Posts: 4
Premium Member CAT Tests
Re: Which of the following equations has 1 + √2 as one of its roots?  [#permalink]

Show Tags

New post 17 Mar 2019, 11:50
How can we use the sum of roots formula here?
We don't have the value of a to be certain?
GMAT Club Bot
Re: Which of the following equations has 1 + √2 as one of its roots?   [#permalink] 17 Mar 2019, 11:50

Go to page   Previous    1   2   [ 23 posts ] 

Display posts from previous: Sort by

Which of the following equations has 1 + √2 as one of its roots?

  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®.