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Homework Help: Boolean Algebra- having trouble solving

  1. Feb 11, 2009 #1
    1. The problem statement, all variables and given/known data

    AB + (A' + B')C + AB


    2. Relevant equations

    I've simplified many problems, but this one is giving me trouble. I know the answer is AB + C, but for some mental reason, I can't seem to come to that answer.

    3. The attempt at a solution

    STEP 1: AB + A'C + B'C + AB
    STEP 2: AB + A'C + B'C <-- AB + AB = AB
    STEP 3: not sure where to go from here...

    ANSWER= AB + C


    Thanks for any help :)
     
  2. jcsd
  3. Feb 12, 2009 #2
    If
    AB + A'C + B'C

    Then
    AB + A'BC + AB'C + A'B'C

    Then
    AB + C(A'B + AB' + A'B')

    It should be obvious that AB + A'B + AB' + A'B' = 1 but how to reduce down to AB + C, I don't know.
     
  4. Feb 12, 2009 #3
    Ok, I figured out the answer... you need to work backwards, as follows;



    Original Equation --- > AB + (A' + B')C + AB

    STEP 1: AB + (A' + B')C + AB
    STEP 2: AB + (A' + B')C <--- AB+AB=AB, so one AB is removed
    STEP 3: AB + (AB)'C <--- On this step you took a step backwards
    Step 4: AB+C <--- Now, according to demorgans theorem, 11, you ca cancel the AB'

    Answer AB+C

    Tough one.....
     
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