It is currently 20 Sep 2017, 04:04

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

Events & Promotions

Events & Promotions in June
Open Detailed Calendar

The operation delta is defined for all nonzero x and y b x

Author Message
TAGS:

Hide Tags

Manager
Joined: 17 Aug 2006
Posts: 87

Kudos [?]: 20 [0], given: 0

The operation delta is defined for all nonzero x and y b x [#permalink]

Show Tags

29 Jul 2007, 11:56
1
This post was
BOOKMARKED
00:00

Difficulty:

15% (low)

Question Stats:

82% (00:55) correct 18% (01:41) wrong based on 73 sessions

HideShow timer Statistics

The operation # is defined for all nonzero x and y by x#y = x + x/y. If a>0, then 1#(1#a) =

A. a
B. a+1
C. a/(a+1)
D. (a+2)/(a+1)
E. (2a+1)/(a+1)

OPEN DISCUSSION OF THIS QUESTION IS HERE: the-operation-is-defined-for-all-nonzero-x-and-y-by-x-y-162019.html
[Reveal] Spoiler: OA

Last edited by Bunuel on 03 Jan 2014, 05:03, edited 1 time in total.
Renamed the topic, edited the question, added the OA and moved to PS forum.

Kudos [?]: 20 [0], given: 0

SVP
Joined: 01 May 2006
Posts: 1794

Kudos [?]: 165 [0], given: 0

Show Tags

29 Jul 2007, 13:53
(E) for me

o 1 delta a
= 1 + 1/a
= (a + 1)/a

o 1 delta (1 delta a)
= 1 delta ((a + 1)/a)
= 1 + 1/((a + 1)/a)
= 1 + a/(a+1)
= (2*a + 1) / (a + 1)

Kudos [?]: 165 [0], given: 0

GMAT Club Legend
Joined: 07 Jul 2004
Posts: 5039

Kudos [?]: 424 [0], given: 0

Location: Singapore

Show Tags

30 Jul 2007, 23:39
1 delta a = 1 + 1/a
Let 1 delta a be x

Then 1 delta (1 delta a) = 1 delta x = 1 + 1/x. Subsitute in x, to give

1 + 1/(1+1/a) = 1 + a/(a+1) = a+1+a/(a+1) = 2a+1/(a+1)

Kudos [?]: 424 [0], given: 0

Intern
Joined: 05 Dec 2013
Posts: 2

Kudos [?]: [0], given: 0

Re: The operation delta is defined for all nonzero x and y b x [#permalink]

Show Tags

02 Jan 2014, 08:26
Can someone explain the math better on this one? Brunnel, do you mind?

Kudos [?]: [0], given: 0

Math Expert
Joined: 02 Sep 2009
Posts: 41631

Kudos [?]: 124102 [0], given: 12071

Re: The operation delta is defined for all nonzero x and y b x [#permalink]

Show Tags

03 Jan 2014, 05:04
Expert's post
1
This post was
BOOKMARKED
jeremyl3763 wrote:
Can someone explain the math better on this one? Brunnel, do you mind?

The operation # is defined for all nonzero x and y by x#y = x + x/y. If a>0, then 1#(1#a) =
A. a
B. a+1
C. a/(a+1)
D. (a+2)/(a+1)
E. (2a+1)/(a+1)

$$1#(1#a) = 1#(1+\frac{1}{a}) = 1#(\frac{a+1}{a})= 1+ \frac{1}{(\frac{a+1}{a})}=1+\frac{a}{a+1}=\frac{a+1+a}{a+1}=\frac{2a+1}{a+1}$$.

OPEN DISCUSSION OF THIS QUESTION IS HERE: the-operation-is-defined-for-all-nonzero-x-and-y-by-x-y-162019.html
_________________

Kudos [?]: 124102 [0], given: 12071

Math Expert
Joined: 02 Sep 2009
Posts: 41631

Kudos [?]: 124102 [0], given: 12071

Re: The operation delta is defined for all nonzero x and y b x [#permalink]

Show Tags

03 Jan 2014, 05:04

Kudos [?]: 124102 [0], given: 12071

Re: The operation delta is defined for all nonzero x and y b x   [#permalink] 03 Jan 2014, 05:04
Similar topics Replies Last post
Similar
Topics:
1 The operation T is defined by x T y=1/x+1/y for all nonzero numbers x 3 10 Oct 2011, 20:09
1 If the operation # is defined for all non-zero x and y by the equation 3 01 Jun 2017, 17:26
2 The operation # is defined for all non-zero x and y by the equation x# 3 01 Jun 2017, 19:47
1 The operation is defined for all non-zero x and y by the equation x 2 19 May 2017, 22:46
16 The operation # is defined for all nonzero x and y by x # y 10 06 Jun 2017, 14:05
Display posts from previous: Sort by