BREAKING: Target Test Prep releases Brand New 2026 On Demand GMAT prep course

Redeem

Help with Quadratic Equations

This topic has expert replies
Post new topic Post Reply
Previous Topic Next Topic
Source: — Data Sufficiency |
User avatar
Legendary Member
Posts: 748
Joined: Sun Jan 31, 2010 7:54 am
Thanked: 46 times
Followed by:3 members

by outreach » Mon Mar 08, 2010 12:45 pm
i feel the answer is E. using both u cannot solve the equ

Question is what is the value of (x-y)(x+y)?

option A
x=2y+2

option B
(x-y)(x+1)=1
x^2+x-yx-y=1


combining both
subst value of x from opt A in eqn obt in opt B
(2y+2)^2+2y+2-y(2y+2)-y=1
4y^2+8y+4+2y+2-2y^2-2y=1
solving we get 2 values of y

if option B was (x+y) instead of (x+1) then answer would have been B
-------------------------------------
--------------------------------------
General blog
https://amarnaik.wordpress.com
MBA blog
https://amarrnaik.blocked/
Top
Newbie | Next Rank: 10 Posts
Posts: 4
Joined: Thu Feb 25, 2010 4:42 am

by yossi » Mon Mar 08, 2010 12:49 pm
outreach wrote:i feel the answer is E. using both u cannot solve the equ

Question is what is the value of (x-y)(x+y)?

option A
x=2y+2

option B
(x-y)(x+1)=1
x^2+x-yx-y=1


combining both
subst value of x from opt A in eqn obt in opt B
(2y+2)^2+2y+2-y(2y+2)-y=1
4y^2+8y+4+2y+2-2y^2-2y=1
solving we get 2 values of y

if option B was (x+y) instead of (x+1) then answer would have been B
I think you right! I am using not so great books. They claim the answer to be B as well...

So fratrating to have mistakes in your GMAT books!!!

Thank you very much
Thank you very much
Top
Post new topic Post Reply
• Page 1 of 1