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Algebra!

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by Ahmed MS » Sat Oct 29, 2011 5:42 pm
Q: If XY+Z=X(Y+Z), then which of the following must be true?

1. X=0,Z=0
2. X=1,Y=1
3. Y=1,Z=0
4. X=1, Y=0
5. X=1,Z=0

OA is 5.
Very simple problem but I got confused. Please help me guys!


Cheers!
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by user123321 » Sat Oct 29, 2011 6:51 pm
Ahmed MS wrote:Q: If XY+Z=X(Y+Z), then which of the following must be true?

1. X=0,Z=0
2. X=1,Y=1
3. Y=1,Z=0
4. X=1, Y=0
5. X=1,Z=0

OA is 5.
Very simple problem but I got confused. Please help me guys!


Cheers!
xy+z = xy + xz
z = xz
z(x-1) = 0
x=1 or z=0

user123321
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Want to do it right the first time.
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by tpr-becky » Sun Oct 30, 2011 8:23 am
if xy + z = x(y + z) you have to apply the distributive rule to get xy + z = xy + xz.subtract out the xy to get z = xz.

The only way for z to equal xz is if z = 0 or x = 1

The answers are written confusingly here- it is clear that the comma is supposed to be an "or" but without that clarification the problem is difficult to answer.
Becky
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