more basic boolean

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

  1. Airmax

    Thread Starter New Member

    Feb 17, 2008
    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 !!!


  2. Papabravo


    Feb 24, 2006
    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
    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


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

    Active Member

    Nov 23, 2006
    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