Find all School-related info fast with the new School-Specific MBA Forum

 It is currently 04 May 2015, 19:21

### 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

# x and y are consecutive positive integers and x>y. X^2 -

Author Message
TAGS:
CEO
Joined: 21 Jan 2007
Posts: 2764
Location: New York City
Followers: 9

Kudos [?]: 349 [0], given: 4

x and y are consecutive positive integers and x>y. X^2 - [#permalink]  06 Nov 2007, 21:49
x and y are consecutive positive integers and x>y.

X^2 - 1 > Y^2 - 4y + x - 1

Which represents all the possible values of Y?

y>=0
y>0
y>1
y>7
y>8
CEO
Joined: 21 Jan 2007
Posts: 2764
Location: New York City
Followers: 9

Kudos [?]: 349 [0], given: 4

Re: inequalities [#permalink]  06 Nov 2007, 22:01
bmwhype2 wrote:
x and y are consecutive positive integers and x>y

X^2 - 1 > Y^2 - 4y + x - 1

Which represents all the possible values of Y?

y>=0
y>0
y>1
y>7
y>8

simplifying the equation we get
X(x+1) > y(y+4)
(y+1) (y+1-1)> y(y-4)
y+1 > y-4
1 > 4

can someone elaborate on why y+1 > y-4 becomes 1 > 4?????
SVP
Joined: 01 May 2006
Posts: 1805
Followers: 8

Kudos [?]: 99 [0], given: 0

Re: inequalities [#permalink]  06 Nov 2007, 23:15
bmwhype2 wrote:
bmwhype2 wrote:
x and y are consecutive positive integers and x>y

X^2 - 1 > Y^2 - 4y + x - 1

Which represents all the possible values of Y?

y>=0
y>0
y>1
y>7
y>8

simplifying the equation we get
X(x+1) > y(y+4)
(y+1) (y+1-1)> y(y-4)
y+1 > y-4
1 > 4

can someone elaborate on why y+1 > y-4 becomes 1 > 4?????

We have 1 > -4 not 1 > 4.... That means it's always true for y > 0
SVP
Joined: 29 Aug 2007
Posts: 2497
Followers: 57

Kudos [?]: 556 [0], given: 19

Re: inequalities [#permalink]  07 Nov 2007, 00:34
bmwhype2 wrote:
bmwhype2 wrote:
x and y are consecutive positive integers and x>y

X^2 - 1 > Y^2 - 4y + x - 1

Which represents all the possible values of Y?

y>=0
y>0
y>1
y>7
y>8

simplifying the equation we get
X(x+1) > y(y+4)
(y+1) (y+1-1)> y(y-4)
y+1 > y-4
1 > 4

can someone elaborate on why y+1 > y-4 becomes 1 > 4?????

x^2 - 1 > y^2 - 4y + x - 1
x^2 - x > y^2 - 4y
x (x-1) > y (y-4)
(y+1) (y+1-1)> y(y-4)
y(y+1) > y(y-4)
y(y+1) - y(y-4) > 0
y (y+1-y+4) > 0
y (y+1-y+4) > 0
y (5) > 0
y > 0
Current Student
Joined: 28 Dec 2004
Posts: 3391
Location: New York City
Schools: Wharton'11 HBS'12
Followers: 13

Kudos [?]: 181 [0], given: 2

I agree y>0

try any value of y..i.e 1/2 /1/4..5 it holds
SVP
Joined: 28 Dec 2005
Posts: 1583
Followers: 2

Kudos [?]: 88 [0], given: 2

i get until x(x-1) > y(y-4) .... how do you get to the next step ?
Senior Manager
Joined: 06 Aug 2007
Posts: 370
Followers: 1

Kudos [?]: 23 [0], given: 0

pmenon wrote:
i get until x(x-1) > y(y-4) .... how do you get to the next step ?

pmenon..since x>y and they are consecutive so x = y + 1.
SVP
Joined: 01 May 2006
Posts: 1805
Followers: 8

Kudos [?]: 99 [0], given: 0

Re: inequalities [#permalink]  02 Dec 2007, 23:00
bmwhype2 wrote:
Fig wrote:
bmwhype2 wrote:
bmwhype2 wrote:
x and y are consecutive positive integers and x>y

X^2 - 1 > Y^2 - 4y + x - 1

Which represents all the possible values of Y?

y>=0
y>0
y>1
y>7
y>8

simplifying the equation we get
X(x+1) > y(y+4)
(y+1) (y+1-1)> y(y-4)
y+1 > y-4
1 > 4

can someone elaborate on why y+1 > y-4 becomes 1 > 4?????

We have 1 > -4 not 1 > 4.... That means it's always true for y > 0

why?

Because:
o The domain of definition for y is "all positive integers"... So y > 0
o 1 > -4 remains valid all time... So on the domain of definition for y.

Manager
Joined: 03 Sep 2006
Posts: 233
Followers: 1

Kudos [?]: 5 [0], given: 0

Ans B (the same method as GMAT TIGER)
SVP
Joined: 28 Dec 2005
Posts: 1583
Followers: 2

Kudos [?]: 88 [0], given: 2

Ended up with B. woo hoo
Similar topics Replies Last post
Similar
Topics:
2 If x and y are integers, is (x−1)>y? 7 04 Feb 2014, 14:43
4 Are the positive integers x and y consecutive? 4 06 Jan 2013, 07:04
13 For positive integers x and y, x^2 = 350y. Is y divisible 13 09 May 2012, 15:25
122 If p, x, and y are positive integers, y is odd, and p = x^2 23 14 Aug 2009, 11:49
x and y are consecutive positive integers and x>y x^2 5 24 Nov 2006, 22:28
Display posts from previous: Sort by