Is the positive integer x odd?
(1) x = y^2 + 4y +6
(2) x = 9z^2 + 7z - 10
please explain, thank
OA : B
Source: Manhattan challenge problem
Manhattan_ Is the postive integer x odd
This topic has expert replies
-
- Senior | Next Rank: 100 Posts
- Posts: 48
- Joined: Wed Aug 27, 2008 9:58 am
- Vemuri
- Legendary Member
- Posts: 682
- Joined: Fri Jan 16, 2009 2:40 am
- Thanked: 32 times
- Followed by:1 members
Question is asking if x is odd?
Stmt 1: x = y^2 + 4y +6 . We do not know if y is even or odd
If y is odd ==> x = odd+even+even ==> x = odd
If y is even ==> x = even+even+even ==> even
So, this statement is not sufficient
Stmt2: x = 9z^2 + 7z - 10. We do not know if z is even or odd
If z is odd ==> x = odd+odd-even = even
If z is even ==> x = even+even-even = even
This statement is sufficient.
Hence B is the answer.
Stmt 1: x = y^2 + 4y +6 . We do not know if y is even or odd
If y is odd ==> x = odd+even+even ==> x = odd
If y is even ==> x = even+even+even ==> even
So, this statement is not sufficient
Stmt2: x = 9z^2 + 7z - 10. We do not know if z is even or odd
If z is odd ==> x = odd+odd-even = even
If z is even ==> x = even+even-even = even
This statement is sufficient.
Hence B is the answer.