# Which of the following Boolean rules is correct?

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Which of the following Boolean rules is correct?
1. A + 0 = 0
2. A + 1 = 1
3. $\overline {A + A} = \overline {A.A}$
4. $A + A.B = \overline {A+B}$

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Correct Answer - Option 2 : A + 1 = 1

Concept:

All Boolean algebra laws are shown below

 Name AND Form OR Form Identity law 1.A = A 0 + A = A Null Law 0.A = 0 1 + A = 1 Idempotent Law A. A = A A + A = A Inverse Law AA’ = 0 A + A’ = 1 Commutative Law AB = BA A + B = B + A Associative Law (AB)C (A + B) + C = A + (B + C) Distributive Law A + BC = (A + B) (A + C) A (B + C) = AB + AC Absorption Law A (A + B) = A A + AB = A De Morgan’s Law (AB)’ = A’ + B’ (A + B)’ = A’B’