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

 It is currently 27 Jun 2019, 04:10

### 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

# If xθy=x·y(x−y) for all x and y, then (1θ2)θ3=

Author Message
TAGS:

### Hide Tags

Retired Moderator
Joined: 29 Apr 2015
Posts: 831
Location: Switzerland
Concentration: Economics, Finance
Schools: LBS MIF '19
WE: Asset Management (Investment Banking)
If xθy=x·y(x−y) for all x and y, then (1θ2)θ3=  [#permalink]

### Show Tags

11 Jun 2015, 13:11
1
2
00:00

Difficulty:

5% (low)

Question Stats:

88% (00:55) correct 12% (01:24) wrong based on 124 sessions

### HideShow timer Statistics

If xθy=x·y(x−y) for all x and y, then (1θ2)θ3=

A. −42
B. −30
C. −6
D. 6
E. 30

_________________
Saving was yesterday, heat up the gmatclub.forum's sentiment by spending KUDOS!

PS Please send me PM if I do not respond to your question within 24 hours.
Math Expert
Joined: 02 Sep 2009
Posts: 55804
Re: If xθy=x·y(x−y) for all x and y, then (1θ2)θ3=  [#permalink]

### Show Tags

11 Jun 2015, 13:19
reto wrote:
If xθy=x·y(x−y) for all x and y, then (1θ2)θ3=

A. −42
B. −30
C. −6
D. 6
E. 30

$$xθy = x*y(x - y)$$

$$(1θ2) = 1*2(1 - 2) = -2$$
$$-2θ3 = -2*3(-2 - 3) = 30$$

_________________
Math Expert
Joined: 02 Sep 2009
Posts: 55804
Re: If xθy=x·y(x−y) for all x and y, then (1θ2)θ3=  [#permalink]

### Show Tags

11 Jun 2015, 13:27
Bunuel wrote:
reto wrote:
If xθy=x·y(x−y) for all x and y, then (1θ2)θ3=

A. −42
B. −30
C. −6
D. 6
E. 30

$$xθy = x*y(x - y)$$

$$(1θ2) = 1*2(1 - 2) = -2$$
$$-2θ3 = -2*3(-2 - 3) = 30$$

Similar questions: Operations/functions defining algebraic/arithmetic expressions
_________________
Current Student
Affiliations: Scrum Alliance
Joined: 09 Feb 2010
Posts: 75
Location: United States (MI)
Concentration: Strategy, General Management
GMAT 1: 600 Q48 V25
GMAT 2: 710 Q48 V38
WE: Information Technology (Retail)
If xθy=x·y(x−y) for all x and y, then (1θ2)θ3=  [#permalink]

### Show Tags

12 Jun 2015, 09:41
1
I have often seen people getting confused by strange operators.

So to avoid confusion, I usually substitute the strange operator with a function.

In this case,

$$xθy$$ can be written as $$f(x,y)$$

$$xθy = f(x,y) = x * y * (x - y)$$

So, $$(1θ2)θ3$$ can be written as $$f(f(1,2),3)$$

Solving this in stages,

$$1θ2 = f(1,2) = 1 * 2 * (1 - 2) = -2$$

and so it now becomes

$$f(-2,3) = -2 * 3 * (-2 - 3) = -2 * 3 * -5 = -6 * -5 = 30$$

OA = E
_________________
Non-Human User
Joined: 09 Sep 2013
Posts: 11450
Re: If xθy=x·y(x−y) for all x and y, then (1θ2)θ3=  [#permalink]

### Show Tags

29 Dec 2018, 11:37
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.
_________________
Re: If xθy=x·y(x−y) for all x and y, then (1θ2)θ3=   [#permalink] 29 Dec 2018, 11:37
Display posts from previous: Sort by