Exam-style question
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Which Boolean expression represents the output Y that is 1 when exactly two of the inputs A, B and C are 1?.
- A.A B C
- B.A B + A C + B C
- C.A B C + A' B' C' + ...
- D.A + B + C
Model answer
What a good answer should say
- A B + A C + B C
Explanation
Why this works
Boolean algebra rule: sum of products for exactly two true -> Y = A B + A C + B C -> The Boolean expression for exactly two true inputs is AB + AC + BC.
Common mistake
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