If P is a set of integers and 3 is in P, are all the positive multiples of 3 in P?
a)If x is in P, then x+3 is in P
b)If x is in P then x-3 is in P
set P
This topic has expert replies
the ans according to me should be A but it is given to be C
Can someone explain how?
my reasoning says that
if 3 is in P and x+3 is also in P , then all positive multiples of 3 will be in P.
this is because for both the above conditions to be valid , the value of x should be 0.
where am i faltering?
Can someone explain how?
my reasoning says that
if 3 is in P and x+3 is also in P , then all positive multiples of 3 will be in P.
this is because for both the above conditions to be valid , the value of x should be 0.
where am i faltering?
-
- Legendary Member
- Posts: 752
- Joined: Sun May 17, 2009 11:04 pm
- Location: Tokyo
- Thanked: 81 times
- GMAT Score:680
you are rightclar wrote:the ans according to me should be A but it is given to be C
Can someone explain how?
my reasoning says that
if 3 is in P and x+3 is also in P , then all positive multiples of 3 will be in P.
this is because for both the above conditions to be valid , the value of x should be 0.
where am i faltering?
A should be the answer.
because if 3 is there in the set then all the multiples must be there
a) SUFF
b)NOT SUFF, because it will depend upon what the set is
it can be {...-6,-3,0,3}
or it can be the infinite set {...-6,-3,0,3,6.....}
NOT SUFF
The powers of two are bloody impolite!!
- PussInBoots
- Master | Next Rank: 500 Posts
- Posts: 157
- Joined: Tue Oct 07, 2008 5:47 am
- Thanked: 3 times
-
- Senior | Next Rank: 100 Posts
- Posts: 36
- Joined: Sun Jun 21, 2009 12:09 pm
- Thanked: 1 times
- GMAT Score:700
Why C?
I got E.
If X were 2, then we would get 5 or -1.
If X were 3, then we would get 6 or 3, hence multiple of 3.
I got E.
If X were 2, then we would get 5 or -1.
If X were 3, then we would get 6 or 3, hence multiple of 3.