Boolean Simplification - Confused

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I am doing some mathematics, and I am currently stuck on something. I do not understand this part at all, how can one approach this?

No variable is used here.

Problem:

Simplify the following Boolean expressions as far as possible, using and stating which Boolean laws and axioms you use at every step.

$$(x+xy)'y'+x'$$

I simply have no idea how to approach this, and what is the best way to remember the steps in terms of approaching this problem and simplifying as far as possible.


  1. $(x+xy)'y'+x'$
  2. $(x' \cdot (xy)')y'+x'$ (First deMorgan law)
  3. $(x' + (x' + y'))y'+x'$ (Second deMorgan law)
  4. $(x'x' + x'y')y'+x'$ (Distributive law)

EDIT: This is how far I am getting, and I am still somehow overwhelmed and confused.

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There are surely many ways to simplify the expression $$(x + xy)'y' + x'.$$ One is to use the absorption law $x + xy = x$ twice (along with commutativity, i suppose) to arrive at $$(x + xy)'y' + x' = x'.$$ If you have not yet proven this law in your course, you can do so by using more elementary laws, say by an argument like $$x + xy = x \cdot 1 + x \cdot y = x(1 + y) = x \cdot 1 = x,$$ or by making a truth table.