ISRO CSE 2011 | Question: 6

Question

Evaluate $\text{(X xor Y) xor Y}?$

• A. All $\text{1's}$
• B. All $\text{0's}$
• C. $\text{X}$
• D. $\text{Y}$

Answer 1

(X⊕Y)⊕Y=(XY'+XY')Y'+(XY+X'Y')Y

               =XY'+XY

               =X

Another way to solve problem

XOR operation is associative

(X⊕Y)⊕Y=X⊕(Y⊕Y)

              =X⊕0

               =X

Comments

Hey, That's not me.

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@Amar: My bad. :)

I might need new glasses.

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   nn input XOR and  n input XOR  

I guess u mean Xor and Xnor, nice Info.. 

Answer 2

X   Y   Xxor Y=C       Cxor Y=result

0   0     0                      0=X

0   1     1                      0=X

1   0     1                      1=X

1   1     0                      1=X

Therefore, answer is X.(An easy way to solve this type of question or if number of variables is restricted to 3.

Answer 3

(X⊕Y)⊕Y = (X⊕Y)Y' + (X⊕Y)'Y =  (X⊕Y)Y'  +  (X⊙Y)Y = (X'Y + XY')Y + (XY + X'Y')Y

                                                                                 = X'Y + XY = (X'+X)Y = Y  

Comments

wrong answer. you did mistake while solving.check it once carefully. you will got X as answer.