|
Author |
Message |
|
TAGS:
|
|
|
Manager
Joined: 21 Sep 2006
Posts: 111
Location: Where you mind is
Followers: 1
Kudos [?]:
0
[0], given: 0
|
If xy + z = x(y+z), which of the following must be true? A. [#permalink]
 23 Dec 2007, 21:47
If xy + z = x(y+z), which of the following must be true?
A. x = 0, z = 0
B. x = 1, y = 1
C. y = 1, z = 0
D. x = 1, y = 0
E. x = 1, z = 0
What I did was:
Step 1: xy + z = xy + xz
Step 2: Substitute the values in the answer options to see which one gives equal values. But the problem was, i found 3 such answers!
B: 1 + z = 1 + z
D: z = z
E: y = y
The OA is E. Can you guys please help to explain this?
Thanks.
|
|
|
|
|
|
|
Manager
Joined: 01 Sep 2007
Posts: 105
Location: Astana
Followers: 1
Kudos [?]:
14
[0], given: 0
|
hi there
xy+z=xy+xz =>
z = xz
z- xz=0
z(1-x)=0
z=0, x=1
|
|
|
|
|
|
SVP
Joined: 28 Dec 2005
Posts: 1612
Followers: 1
Kudos [?]:
53
[0], given: 2
|
expand and rearranging the given equation gives you:
xy-xy+z-xz=0
z-xz=0
z(1-x)=0
the only way for that to be true is for one of the terms to be zero, namely, either z=0 or 1-x=0, i.e. x=1.
Option E states this
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
Similar topics |
Author |
Replies |
Last post |
|
Similar
Topics:
|
 |
|
|
If xy +z = x(y+z) which of the following must be true? A)
|
Matrix02 |
3 |
05 Nov 2006, 17:11 |
|
|
|
|
If xy + z = x(y+z), which of the following must be true?
|
LM |
5 |
23 Jun 2007, 02:33 |
|
|
|
|
If xy+z = x(y+z), which of the following must be true? 1,
|
pinal2 |
2 |
09 Dec 2007, 20:08 |
|
|
|
|
If xy+z = x(y+z), which of the following must be true? a.
|
chica |
4 |
31 Mar 2008, 00:36 |
|
|
|
|
If xy + z = x(y+z), which of the following must be true? A.
|
jimmyjamesdonkey |
3 |
18 May 2008, 18:14 |
|
|
|
|
|
|
close
