Consider the following circuit to make it a Tautology the [?] should be
2005
Consider the following circuit
to make it a Tautology the [?] should be
- A.
NAND Gate
- B.
AND Gate
- C.
OR Gate
- D.
EX-OR Gate
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Correct answer: A
To make F a tautology, the output must always be 1. The top OR gate outputs (X + Y). If `[?]` is a NAND gate, it outputs (XY)'. The final OR sums them: F = X + Y + (XY)'. Using De Morgan's, (XY)' = X' + Y', so F = X + Y + X' + Y'. Since X+X'=1 and Y+Y'=1, F=1. Therefore, `[?]` is a NAND gate.
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