# Logic Gates (NAND to AND Gates)

couldnt understand why the input is ( (XY)' (XY)' ) ' , IMO , it should be ((XY)' ) ' . because the 2nd logic gates receive (XY)' input from the first logic gates , and the second logic gates act as inverter for the first logic gates.

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## Answers and Replies

jedishrfu
Mentor
I think they did that because the (XY)' is the input to the second gate and both inputs are tied together then they said (XY)'(XY)' and the second gates output is then ( (XY)' (XY)' ) ' which can be reduced to ( (XY)' ) ' and the double negative to simply XY so it shows that two NAND gates can be used to construct an AND gate.

• desmond iking
I think they did that because the (XY)' is the input to the second gate and both inputs are tied together then they said (XY)'(XY)' and the second gates output is then ( (XY)' (XY)' ) ' which can be reduced to ( (XY)' ) ' and the double negative to simply XY so it shows that two NAND gates can be used to construct an AND gate.
Can I say the input is ((XY)' ) ' , which is also can be reduced to XY ?

jedishrfu
Mentor
Yes, I believe thats right.

• desmond iking