more basic boolean

Discussion in 'Math' started by Airmax, Feb 22, 2008.

  1. Airmax

    Thread Starter New Member

    Feb 17, 2008
    3
    0
    Hey there guys, how is everyone ?

    I have another basic boolean question for the gurus out there. I am slowly working my way through my work book and came across this question.

    prove that A+AB=A using boolean algebra.

    Now i know that A+AB=A as it a basic rule used to simplify boolean expressions, however actually going through the process is a little difficult for me. When i looked at the answer it showed this:

    Step 1. A + AB = A
    Step 2. A(1 + B) = A
    Step 3. A=A

    What I was needing help with is I dont know what they have done with step 1 to get to step 2. I see they have factored out the A out of both terms but i dont understand how they have expanded the B term and then canceled it out. If someone could briefly explain to me the steps to go through it would be great !!!

    Cheers

    Trev
     
  2. Papabravo

    Expert

    Feb 24, 2006
    10,137
    1,786
    A logical OR operation indicated by the `+' symbol says

    1 .OR. B = 1 which means B can either be a 0 or a 1, we dont care because

    1 .OR. 0 = 1 and
    1 .OR. 1 = 1

    Get it?
    I knew you would
     
  3. scubasteve_911

    Senior Member

    Dec 27, 2007
    1,202
    1
    So, as you said, they factored out the A term. You can see, no matter what state of B, there will be a logic 1 resulting from the 1+B term.

    So, if B=0, then A(1+0)=A, if B=1, then A(1+1)=A

    Steve

    Papabravo beat me by a millisecond! :p
     
  4. aliashar86

    Active Member

    Nov 23, 2006
    71
    0
    its simple, in the first step a common was taken which u must have done in your earlier grades in maths (am talking abt factorization).

    and second step is given correctly by "Scubasteve 911"


    hope its clear to u
     
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