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gmat prep question

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IMO E

by iamcste » Sat Nov 08, 2008 8:43 am
xy+z=xy+xz

xy cancels

z=xz

xz-z=0

z(x-1)=0

x=1, z=0

IMO E
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Re: gmat prep question

by logitech » Sat Nov 08, 2008 8:45 am
steinbock wrote:If xy + z = x(y+z), which of the following must be true?

A) x=0 and z=0
B) x=1 and y=1
C) y=1 and z=0
D) x=1 and y=0
E) x=1 and z=0

OA is E

Can someone please provide an explanation? Thanks.
xy + z = x(y+z)

xy+z=xy+xz ( we can cancel both XZ from the sides )

z=xz

Z-xz=0

z(1-x)=0

z=0

OR

1-x=0

SO, x=1 and z= 0
LGTCH
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gmat prep question, Plz. help

by gmat009 » Mon Nov 10, 2008 12:22 pm
steinbock wrote:If xy + z = x(y+z), which of the following must be true?

A) x=0 and z=0
B) x=1 and y=1
C) y=1 and z=0
D) x=1 and y=0
E) x=1 and z=0

OA is E

Can someone please provide an explanation? Thanks.
Can someone plz. help me understand this problem.
I am getting z(1-x)=0
Therefore , z=0 or x=1
Also xy=0 as it got cancelled from both sides.
So if x=1 then y=0 to get xy=0
So I am getting ans D instead of E
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Re: gmat prep question, Plz. help

by logitech » Mon Nov 10, 2008 12:55 pm
gmat009 wrote:
steinbock wrote:If xy + z = x(y+z), which of the following must be true?

A) x=0 and z=0
B) x=1 and y=1
C) y=1 and z=0
D) x=1 and y=0
E) x=1 and z=0

OA is E

Can someone please provide an explanation? Thanks.
Can someone plz. help me understand this problem.
I am getting z(1-x)=0
Therefore , z=0 or x=1
Also xy=0 as it got cancelled from both sides.
So if x=1 then y=0 to get xy=0
So I am getting ans D instead of E
Two things:

1) XY did not cancelled becaused it was equal to ZERO, but it was at the both side of the equation

bla bla + XY = cha cha + XY

Bla bla = Cha CHa

2) You are solving the equation for Z and X so choose E
LGTCH
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Re: gmat prep question, Plz. help

by jimmiejaz » Mon Nov 10, 2008 1:55 pm
logitech wrote:
gmat009 wrote:
steinbock wrote:If xy + z = x(y+z), which of the following must be true?

A) x=0 and z=0
B) x=1 and y=1
C) y=1 and z=0
D) x=1 and y=0
E) x=1 and z=0

OA is E

Can someone please provide an explanation? Thanks.
Can someone plz. help me understand this problem.
I am getting z(1-x)=0
Therefore , z=0 or x=1
Also xy=0 as it got cancelled from both sides.
So if x=1 then y=0 to get xy=0
So I am getting ans D instead of E
Two things:

1) XY did not cancelled becaused it was equal to ZERO, but it was at the both side of the equation

bla bla + XY = cha cha + XY

Bla bla = Cha CHa

2) You are solving the equation for Z and X so choose E
Hi Logitech,

Have sent a pm to you... Pls respond!!!!

Rajiv
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by schakiiieee » Sun Nov 16, 2008 5:52 am
Shouldnt it much rather say "or" instead of "and" in answer choice E? (E is still the best answer choice)
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by stop@800 » Sun Nov 16, 2008 6:05 am
The Qn says which of the following must be TRUE
and also the answer choice has
x=1 and z=0

The "and"

I think this should be OR

if z=0, any value is acceptable for x
so E is also not correct, as the Qn is must be true
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