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# If xy +z = x(y+z) which of the following must be true? A)

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Senior Manager
Joined: 13 Sep 2006
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Location: New York
If xy +z = x(y+z) which of the following must be true? A) [#permalink]

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05 Nov 2006, 17:11
This topic is locked. If you want to discuss this question please re-post it in the respective forum.

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 or y=0
E) X=1 or z=0

What is the a quick way to do this one?
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"Never let the fear of striking out get in your wayâ€

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05 Nov 2006, 17:17
(E)

xy +z = x(y+z)
<=> xy + z = xy +xz
<=> z = xz

Implies that
o z=0 and x is any real number
or
o z is any real number and x=1
Senior Manager
Joined: 13 Sep 2006
Posts: 279
Location: New York

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05 Nov 2006, 17:26
Thanks Fig for the great explanation!
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"Never let the fear of striking out get in your wayâ€

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Joined: 01 May 2006
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06 Nov 2006, 01:54
U are welcome
06 Nov 2006, 01:54
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