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

 It is currently 24 Aug 2016, 05:52

### 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
CEO
Joined: 21 Jan 2007
Posts: 2756
Location: New York City
Followers: 9

Kudos [?]: 730 [0], given: 4

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

### Show Tags

06 Nov 2007, 22:49
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

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: 2756
Location: New York City
Followers: 9

Kudos [?]: 730 [0], given: 4

### Show Tags

06 Nov 2007, 23:01
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: 1798
Followers: 9

Kudos [?]: 137 [0], given: 0

### Show Tags

07 Nov 2007, 00:15
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: 2492
Followers: 66

Kudos [?]: 692 [0], given: 19

### Show Tags

07 Nov 2007, 01:34
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: 3385
Location: New York City
Schools: Wharton'11 HBS'12
Followers: 14

Kudos [?]: 257 [0], given: 2

### Show Tags

07 Nov 2007, 08:11
I agree y>0

try any value of y..i.e 1/2 /1/4..5 it holds
SVP
Joined: 28 Dec 2005
Posts: 1575
Followers: 3

Kudos [?]: 129 [0], given: 2

### Show Tags

02 Dec 2007, 16:04
i get until x(x-1) > y(y-4) .... how do you get to the next step ?
Senior Manager
Joined: 06 Aug 2007
Posts: 368
Followers: 1

Kudos [?]: 32 [0], given: 0

### Show Tags

02 Dec 2007, 18:31
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: 1798
Followers: 9

Kudos [?]: 137 [0], given: 0

### Show Tags

03 Dec 2007, 00:00
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 [?]: 18 [0], given: 0

### Show Tags

03 Dec 2007, 00:36
Ans B (the same method as GMAT TIGER)
SVP
Joined: 28 Dec 2005
Posts: 1575
Followers: 3

Kudos [?]: 129 [0], given: 2

### Show Tags

15 Dec 2007, 12:16

Ended up with B. woo hoo
Display posts from previous: Sort by