DS X =3?

This topic has expert replies
Source: — Data Sufficiency |

User avatar
Master | Next Rank: 500 Posts
Posts: 435
Joined: Mon Mar 15, 2010 6:15 am
Thanked: 32 times
Followed by:1 members

by eaakbari » Tue Apr 06, 2010 2:04 am
I think your question may have been

(1) x = (-3y+3)/(1-y) OR (1) x = (3y-3)/(1-y)

If it is so answer is C


If not IMO E

User avatar
Legendary Member
Posts: 1560
Joined: Tue Nov 17, 2009 2:38 am
Thanked: 137 times
Followed by:5 members

by thephoenix » Tue Apr 06, 2010 2:29 am
s1)--->x=3(y+1)/(y-1) x varies wrt y..insuff

s2)---->insuff

E

User avatar
Legendary Member
Posts: 1275
Joined: Thu Sep 21, 2006 11:13 pm
Location: Arabian Sea
Thanked: 125 times
Followed by:2 members

by ajith » Tue Apr 06, 2010 5:25 am
gmatmachoman wrote:Is x = 3?

(1) x =( −3y − 3)/(1− y)

(2)|x|/ x + x *| x| > 0
E

Had the question been

(1) x =( −3y + 3)/(1− y)

(2)|x|/ x + x *| x| > 0

Then C
Always borrow money from a pessimist, he doesn't expect to be paid back.

Senior | Next Rank: 100 Posts
Posts: 65
Joined: Wed Nov 25, 2009 6:33 pm
Thanked: 3 times

by dxgamez » Tue Apr 06, 2010 10:13 pm
Hi Guys, could you help me understand why the answer is C. I thought A was sufficient.

if it was (1) x = (-3y+3)/(1-y) then x = 3(1-y)/(1-y)...I was thinking we could strike off (1-y) then x=3 right?

or I should abandon this in DS cos y could be 1 and render x to be 0? is this the thinking?

also, st2 means that x should be positive so that expression in st2 > 0. is this right or wrong?

User avatar
Master | Next Rank: 500 Posts
Posts: 435
Joined: Mon Mar 15, 2010 6:15 am
Thanked: 32 times
Followed by:1 members

by eaakbari » Tue Apr 06, 2010 10:27 pm
dxgamez wrote:Hi Guys, could you help me understand why the answer is C. I thought A was sufficient.

if it was (1) x = (-3y+3)/(1-y) then x = 3(1-y)/(1-y)...I was thinking we could strike off (1-y) then x=3 right?

or I should abandon this in DS cos y could be 1 and render x to be 0? is this the thinking?

also, st2 means that x should be positive so that expression in st2 > 0. is this right or wrong?
You asked the question and answered it too.

Exactly what your thinking, we cant strike it off as we do not know if its a non zero term, but statement two tells us that x>0 that is it is a non zero term and positive , then C becomes sufficient

Senior | Next Rank: 100 Posts
Posts: 65
Joined: Wed Nov 25, 2009 6:33 pm
Thanked: 3 times

by dxgamez » Tue Apr 06, 2010 10:42 pm
@eaakbari

thanks a lot! now I know how I should think. still far away from how fantastic you guys think though, but working on it.. :-)

Legendary Member
Posts: 610
Joined: Fri Jan 15, 2010 12:33 am
Thanked: 47 times
Followed by:2 members

by kstv » Tue Apr 13, 2010 7:11 pm
ajith wrote: ......................E

Had the question been

(1) x =( −3y + 3)/(1− y)

(2)|x|/ x + x *| x| > 0

Then C
Could you please check this ?
IMHO A