I will take it as (xy)^2 is positive and odd.
(xy)^2 is always positive either xy is positive or negative.
So I need not be true.
(xy)^2 will be odd provided xy is odd, which means both x and y are odd.
So II must be true.
Also if x and y both are odd, x+y must be even. So III also must be true.
integers
This topic has expert replies
Source: Beat The GMAT — Problem Solving |
-
sureshbala
- Master | Next Rank: 500 Posts
- Posts: 319
- Joined: Wed Feb 04, 2009 10:32 am
- Location: Delhi
- Thanked: 84 times
- Followed by:9 members
let 's startnaaga wrote:. If x and y are integers and xy2 is a positive odd integer, which of the following must be true?
Ⅰ. xy is positive.
Ⅱ. xy is odd.
Ⅲ. x + y is even.
folks please explain how many statements of the above are sufficient to answer the question..
xy2 is a positive odd
xy must be odd
so x+y are odd why ? Because what ever time even is even so no even here
both are odd adding 2 odd give even
but we can't say that both are positive since -X- = + so we know they have the same sign
so the sum is even xy odd
that 's all
when there is a will there is a way ... believe in yourself ... kind regards
-
Bidisha800
- Master | Next Rank: 500 Posts
- Posts: 344
- Joined: Sun Sep 28, 2008 11:00 am
- Location: USA
- Thanked: 6 times
- Followed by:1 members
II & III
Drill baby drill !
GMATPowerPrep Test1= 740
GMATPowerPrep Test2= 760
Kaplan Diagnostic Test= 700
Kaplan Test1=600
Kalplan Test2=670
Kalplan Test3=570
GMATPowerPrep Test1= 740
GMATPowerPrep Test2= 760
Kaplan Diagnostic Test= 700
Kaplan Test1=600
Kalplan Test2=670
Kalplan Test3=570
-
earth@work
- Master | Next Rank: 500 Posts
- Posts: 248
- Joined: Mon Aug 11, 2008 9:51 am
- Thanked: 13 times
II & III
(XY)^2 is odd means both x & y are odd
now 4 possibilities:
1) x (positive) & y (negative)
2) x (positive) & y (positive)
3) x (negative) & y (negative)
4) x (negative) & y (positive)
this means I is not always true
II - odd x odd = odd ..true
III - odd + odd = even ....true
(XY)^2 is odd means both x & y are odd
now 4 possibilities:
1) x (positive) & y (negative)
2) x (positive) & y (positive)
3) x (negative) & y (negative)
4) x (negative) & y (positive)
this means I is not always true
II - odd x odd = odd ..true
III - odd + odd = even ....true
