Summer is Coming! Join the Game of Timers Competition to Win Epic Prizes. Registration is Open. Game starts Mon July 1st.

It is currently 21 Jul 2019, 06:44

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

For all numbers a and b, let a#b = (a + b)^2 – 2ab. Which of the follo

  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: 56307
For all numbers a and b, let a#b = (a + b)^2 – 2ab. Which of the follo  [#permalink]

Show Tags

New post 09 Apr 2018, 02:39
00:00
A
B
C
D
E

Difficulty:

  55% (hard)

Question Stats:

59% (02:16) correct 41% (02:24) wrong based on 76 sessions

HideShow timer Statistics


Current Student
User avatar
P
Joined: 18 Aug 2016
Posts: 617
Concentration: Strategy, Technology
GMAT 1: 630 Q47 V29
GMAT 2: 740 Q51 V38
GMAT ToolKit User Reviews Badge
Re: For all numbers a and b, let a#b = (a + b)^2 – 2ab. Which of the follo  [#permalink]

Show Tags

New post 09 Apr 2018, 03:03
2
Bunuel wrote:
For all numbers a and b, let a#b = (a + b)^2 – 2ab. Which of the following must be true?

I. x#y = y#x
II. (x#y)#z = (z#x)#y
III. (x + y)#(x – y) = 2(x#y)

A. I
B. II only
C. III only
D. I and III only
E. II and III only


a#b = (a + b)^2 – 2ab
a#b = \(a^2 + b^2\)

I
x#y = \(x^2 + y^2\) = y#x...Stands

II
(x#y)#z = \((x^2+y^2)^2 + z^2\)
(z#x)#y = \((z^2+x^2)^2 + y^2\)
Not equal

III
(x + y)#(x – y) = 2(x#y)
\((x+y)^2 + (x-y)^2 = 2 (x^2 + y^2)\) = 2 (x#y)

I and III
D
_________________
We must try to achieve the best within us


Thanks
Luckisnoexcuse
GMAT Club Bot
Re: For all numbers a and b, let a#b = (a + b)^2 – 2ab. Which of the follo   [#permalink] 09 Apr 2018, 03:03
Display posts from previous: Sort by

For all numbers a and b, let a#b = (a + b)^2 – 2ab. Which of the follo

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





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