Simplify the boolean equation given below?
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Simplify the boolean equation given below?
Y = (A + B)' + AB + A
**MCQ
Show answer & explanation
The expression simplifies to 1 (always true). By De Morgan's law, (A + B)' = A'B'. Then A'B' + AB + A can be regrouped as A'B' + A(B + 1). Since (B + 1) = 1, we get A'B' + A = 1 because either A is true (making the result 1) or A is false (making A'B' = 1 when B is also false, which covers all cases).
Step-by-step Derivation:
Step 1: Apply De Morgan's law to (A + B)'
(A + B)' = A'B'
Step 2: Substitute back into the expression
Y = A'B' + AB + A
Step 3: Factor out A from the last two terms
Y = A'B' + A(B + 1)
Step 4: Simplify B + 1 (OR with 1 is always 1)
Y = A'B' + A(1)
Y = A'B' + A
Step 5: Use the absorption-like principle: A'B' + A
When A = 1: Y = 0 + 1 = 1
When A = 0: Y = 1·B' + 0 = B'
Step 6: Re-examine using consensus or truth table
A | B | A'B' | AB | A | Y
0 | 0 | 1 | 0 | 0 | 1
0 | 1 | 0 | 0 | 0 | 0 ← Wait, let me recalculate
Step 6 (Corrected): Full truth table evaluation
A | B | (A+B)' | AB | A | (A+B)'+AB+A
0 | 0 | 1 | 0 | 0 | 1
0 | 1 | 0 | 0 | 0 | 0 ← This gives 0, not 1
1 | 0 | 0 | 0 | 1 | 1
1 | 1 | 0 | 1 | 1 | 1
Step 7: Re-analysis - The result is NOT always 1
Looking at row 2: when A=0, B=1, Y=0
So the answer is NOT C.
Step 8: Simplify correctly using Boolean algebra
Y = A'B' + AB + A
Y = A'B' + A(B + 1)
Y = A'B' + A
Y = (A' + A)(B' + A) [using distribution in reverse]
Y = 1 · (A + B')
Y = A + B'
Actually, let me use the correct method:
Y = A'B' + AB + A
Y = A'B' + A(B + 1)
Y = A'B' + A
Using X + X'Y = X + Y:
Y = A + A'B' = A + B' (when we apply the consensus theorem correctly)
Wait - truth table check:
A=0, B=0: 1 + 0 + 0 = 1 ✓ | A + B' = 0 + 1 = 1 ✓
A=0, B=1: 0 + 0 + 0 = 0 ✓ | A + B' = 0 + 0 = 0 ✓
A=1, B=0: 0 + 0 + 1 = 1 ✓ | A + B' = 1 + 1 = 1 ✓
A=1, B=1: 0 + 1 + 1 = 1 ✓ | A + B' = 1 + 0 = 1 ✓
So Y = A + B' is the correct simplification, which matches NEITHER of the given options exactly. However, reviewing the original options and given that none match A + B', let me verify if there's an error in the problem or if I should reconsider.
Given the available options and the requirement to choose from them: The expression does NOT simplify to 1, A', or B' universally. However, examining standard simplification: Y = A'B' + AB + A should yield A + B' by consensus theorem.