title: Simplifying an Expression by Using Boolean Algebra
body: <p>I have this expression: X'YZ'+X'YZ+XY'Z'+XYZ'+XYZ (' means not)
  I know the answer is Y+XZ' but I am stuck in the last part. Can anyone give me a hand?</p>
  
  <p>This is what I got so far:</p>
  
  <pre><code>X'YZ' + X'YZ + XY'Z' + XYZ' + XYZ
  X'YZ' + X'YZ + XZ'(Y' + Y) + XYZ
  X'YZ' + X'YZ + XZ' + XYZ
  X'YZ' + X'YZ + XYZ + XZ'
  Y(X'Z' + X'Z + XZ) + XZ'   
  Y(1) + XZ'   # I am not sure if is there is a rule that makes (X'Z+X'Z+XZ)= 1
  </code></pre>
  
  <p>Thanks</p>