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The output of the given logic circuit is [Figure: A and B feed NAND 1. NAND 2 takes A and the NAND 1 output. An OR gate takes the NAND 1 output and B. NAND 2 and the OR output feed a final NAND giving Y.]

Asked in JEE Main 12th Jan 1st Shift 2019 · Gate combinations and truth tables

Figure: Gate combinations and truth tables
Answer: (2) AB

Step-by-step solution

Let P=AB.

00: P=1, NAND 2 =1, OR =1, Y=0.

01: P=1, NAND 2 =1, OR =1, Y=0.

10: P=1, NAND 2 =0, Y=1.

11: P=0, NAND 2 =1, OR =1, Y=0.

Y=1 only for A=1,B=0: Y=AB.

Why the other options are wrong

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