must be a positive

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must be a positive

by sanju09 » Thu Sep 16, 2010 10:21 pm
If x, y, and z are consecutive non-zero integers, and if x < y < z, which of the following must be a positive odd integer?
(A) x - y - z
(B) x y + z
(C) x + y - z
(D) x z - y
(E) x + y + z


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by shaw3257 » Thu Sep 16, 2010 10:40 pm
sanju09 wrote:If x, y, and z are consecutive non-zero integers, and if x < y < z, which of the following must be a positive odd integer?
(A) x - y - z
(B) x y + z
(C) x + y - z
(D) x z - y
(E) x + y + z
since x < y < z and x , y, z are consecutive integers we know there are two possible cases:

case 1:
x is ODD
y is EVEN
z is ODD

case 2:
x is EVEN
y is ODD
z is EVEN

Now we can quickly go though our multiple choice answers.

When we come across choice D: x z - y

case1: ODD * ODD - EVEN = ODD

case2: EVEN * EVEN - ODD = ODD

choose D

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by sanju09 » Thu Sep 16, 2010 10:43 pm
shaw3257 wrote:
sanju09 wrote:If x, y, and z are consecutive non-zero integers, and if x < y < z, which of the following must be a positive odd integer?
(A) x - y - z
(B) x y + z
(C) x + y - z
(D) x z - y
(E) x + y + z
since x < y < z and x , y, z are consecutive integers we know there are two possible cases:

case 1:
x is ODD
y is EVEN
z is ODD

case 2:
x is EVEN
y is ODD
z is EVEN

Now we can quickly go though our multiple choice answers.

When we come across choice D: x z - y

case1: ODD * ODD - EVEN = ODD

case2: EVEN * EVEN - ODD = ODD

choose D
good D
The mind is everything. What you think you become. -Lord Buddha



Sanjeev K Saxena
Quantitative Instructor
The Princeton Review - Manya Abroad
Lucknow-226001

www.manyagroup.com

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by goyalsau » Thu Sep 16, 2010 11:21 pm
Good work, i was putting in numbers but odd/Even works well, but i think for that you need to be more familiar with this.