City-Data Forum Math Problem......Boolean.......You solve????? (physics, digital)
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11-29-2011, 12:52 PM
 Location: Brawndo-Thirst-Mutilator-Nation 20,888 posts, read 21,709,575 times Reputation: 18112

No, this is NOT my homework, just felt like posting a brain teaser.

Ok here is a Boolean statement:

X + (X * Y) = X

Simplify the equation to the LEFT of the equals sign so it is

************************************************** *

Here is another Boolean statement:

X * (-Y) + Y = X + Y

Simplfy the statement so the equation to the left of the equals sign is reduced to X + Y, SHOW YOUR WORK.

11-29-2011, 02:04 PM
 482 posts, read 1,183,649 times Reputation: 358
Y = 0

11-29-2011, 02:09 PM
 3,287 posts, read 8,896,664 times Reputation: 2354
These are already "solved" on the right side of the equals sign. All you have to do is reverse the sides and you've got the solution.

11-29-2011, 05:52 PM
 2,495 posts, read 4,171,997 times Reputation: 4929
Quote:
 Originally Posted by pcity These are already "solved" on the right side of the equals sign. All you have to do is reverse the sides and you've got the solution.
lol

11-29-2011, 06:06 PM
 Location: Las Flores, Orange County, CA 26,342 posts, read 89,982,757 times Reputation: 17770
Quote:
 Originally Posted by tickyul No, this is NOT my homework, just felt like posting a brain teaser. Ok here is a Boolean statement: X + (X * Y) = X Simplify the equation to the LEFT of the equals sign so it is simply "X", SHOW YOUR WORK. ************************************************** * Here is another Boolean statement: X * (-Y) + Y = X + Y Simplfy the statement so the equation to the left of the equals sign is reduced to X + Y, SHOW YOUR WORK.
X + (X * Y) = X means X or (X and y) so Y is redudent, therefore, only X is required.

X * (-Y) + Y = X + Y means (X and not Y) or Y. Not sure how this equals X or Y because it can only be X if it it is also not Y.

11-29-2011, 07:23 PM
 Location: Brawndo-Thirst-Mutilator-Nation 20,888 posts, read 21,709,575 times Reputation: 18112
Quote:
 Originally Posted by pcity These are already "solved" on the right side of the equals sign. All you have to do is reverse the sides and you've got the solution.

It is about SIMPLIFYING part of the equation.....NOT SOLVING.

11-29-2011, 09:25 PM
 Location: Missouri 4,247 posts, read 3,590,488 times Reputation: 1924
Quote:
 Originally Posted by tickyul No, this is NOT my homework, just felt like posting a brain teaser. Ok here is a Boolean statement: X + (X * Y) = X Simplify the equation to the LEFT of the equals sign so it is simply "X", SHOW YOUR WORK.
1) x + (xy) = x
2) x = x + (xy)

************************************************** *

Quote:
 Originally Posted by tickyul Here is another Boolean statement: X * (-Y) + Y = X + Y Simplfy the statement so the equation to the left of the equals sign is reduced to X + Y, SHOW YOUR WORK.
1) -xy + y = x + y
2) x + y = -xy + y

Flip things around the equal sign. Simple solution to this simple mind.

12-04-2011, 04:31 PM
 Location: Brawndo-Thirst-Mutilator-Nation 20,888 posts, read 21,709,575 times Reputation: 18112
Quote:
 Originally Posted by geofra 1) x + (xy) = x 2) x = x + (xy) ************************************************** * 1) -xy + y = x + y 2) x + y = -xy + y Flip things around the equal sign. Simple solution to this simple mind.

Here is a clue, very useful:

12-04-2011, 10:18 PM
 15,921 posts, read 19,282,482 times Reputation: 7675
Thanks for reminding me why I studied Hot Rod magazine in algebra

12-05-2011, 12:23 AM
 Location: Silicon Valley 3,683 posts, read 9,404,658 times Reputation: 3006
Quote:
 Originally Posted by tickyul X + (X * Y) = X Simplify the equation to the LEFT of the equals sign so it is simply "X", SHOW YOUR WORK.
That's not even the correct way to ask the question. The question should be posed: Simplify X + XY.

X + XY
X(1 + Y) by distributive law
X(1) by identity law
X by identity law

Quote:
 Here is another Boolean statement: X * (NOT Y) + Y = X + Y
X(NOT Y) + Y

X(NOT Y) + Y + XY by above
XY + X(NOT Y) + Y by commutative law
X(Y + NOT Y) + Y by distributive law
X(1) + Y by complement law
X + Y by identity law

That's not a brain teaser for anyone past their first ten minutes in a high school level course in digital circuits.
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