Which of the following is a NOT a correct identity in Boolean Algebra?

2018

Which of the following is a NOT a correct identity in Boolean Algebra?

  1. A.

    A + AB = A

  2. B.

    A(A+B) = B

  3. C.

    AB + AB' = A

  4. D.

    (A+B)(A+B') = A

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Correct answer: B

Option 1 states A(A+B) = B. Using the distributive law, this expands to AA + AB. Since AA equals A and A + AB simplifies to A via absorption, the expression equals A, not B. Therefore, this identity is incorrect.

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