The integer r and s are distinct and each one not equal to 0. if (r^2)(S^2)=-rs which of the following must be true?
i. r=-1
ii. s=1
iii. r-s=0
a) None
b) i only
c) ii only
d) iii only
e) i, ii and iii
5-Day Free Trial
5-day free, full-access trial TTP
Available with Beat the GMAT members only code
MORE DETAILS
integer r and s are distinct
This topic has expert replies
-
harsh.champ
- Legendary Member
- Posts: 1132
- Joined: Mon Jul 20, 2009 3:38 am
- Location: India
- Thanked: 64 times
- Followed by:6 members
- GMAT Score:760
(r^2)(S^2)=-rsNijeesh wrote:The integer r and s are distinct and each one not equal to 0. if (r^2)(S^2)=-rs which of the following must be true?
i. r=-1
ii. s=1
iii. r-s=0
a) None
b) i only
c) ii only
d) iii only
e) i, ii and iii
Hence,rs=-1.
Alos,since both are distinct either can be 1 or -1.Hence,i and ii not surely true.
For iii, r-s = 0(can not be )either -2 or +2.
Answer would be A.
I hope the explanation is helpful.
It takes time and effort to explain, so if my comment helped you please press Thanks button 
Just because something is hard doesn't mean you shouldn't try,it means you should just try harder.
"Keep Walking" - Johnny Walker
Just because something is hard doesn't mean you shouldn't try,it means you should just try harder.
"Keep Walking" - Johnny Walker
-
ajith
- Legendary Member
- Posts: 1275
- Joined: Thu Sep 21, 2006 11:13 pm
- Location: Arabian Sea
- Thanked: 125 times
- Followed by:2 members
s= -1; r = +1 r-s = 2Nijeesh wrote:The integer r and s are distinct and each one not equal to 0. if (r^2)(S^2)=-rs which of the following must be true?
i. r=-1
ii. s=1
iii. r-s=0
a) None
b) i only
c) ii only
d) iii only
e) i, ii and iii
satisfies r^2*s^2 = -rs
Hence none of I, II or III must be true.
A
Always borrow money from a pessimist, he doesn't expect to be paid back.
-
shashank.ism
- Legendary Member
- Posts: 1022
- Joined: Mon Jul 20, 2009 11:49 pm
- Location: Gandhinagar
- Thanked: 41 times
- Followed by:2 members
(r^2)(S^2)=-rs --> rs(rs+1)=0 --> rs=0 or rs=-1Nijeesh wrote:The integer r and s are distinct and each one not equal to 0. if (r^2)(S^2)=-rs which of the following must be true?
i. r=-1
ii. s=1
iii. r-s=0
a) None
b) i only
c) ii only
d) iii only
e) i, ii and iii
so none fits the given expression and hence A
My Websites:
www.mba.webmaggu.com - India's social Network for MBA Aspirants
www.deal.webmaggu.com -India's online discount, coupon, free stuff informer.
www.dictionary.webmaggu.com - A compact free online dictionary with images.
Nothing is Impossible, even Impossible says I'm possible.
www.mba.webmaggu.com - India's social Network for MBA Aspirants
www.deal.webmaggu.com -India's online discount, coupon, free stuff informer.
www.dictionary.webmaggu.com - A compact free online dictionary with images.
Nothing is Impossible, even Impossible says I'm possible.
-
ashforgmat
- Senior | Next Rank: 100 Posts
- Posts: 71
- Joined: Sun Feb 21, 2010 9:16 pm
- Thanked: 3 times
- GMAT Score:750
None Will be my guess since r=-1, s=1 and r=1, s=-1 are the 2 solutions. And none of the choices give this as the answer.
