MADE EASY TEST SERIES

Question

What will be the output of multiplexer shown below ?

Comments

AD'+A'D

Answer 1

$X_{1} = 1.\overline{A}.\overline{B} + 1.\overline{A}.B = \overline{A}(B + \overline{B}) = \overline{A}$

Now, $Y = A.\overline{S_{1}} .\overline{S_{0}}  + X_{1}.S_{1}.\overline{S_{0}}$

Putting, $X_{1} = \overline{A}, S_{1} = D$ and $S_{0} = 0$

$\color{navy}{Y = A.\overline{D} .\overline{0}  + \overline{A}.D.\overline{0} = A\overline{D} + \overline{A}D}$

Comments

sorry, I meant I2 only. Are you getting my doubt?

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Yes, Your are right. We will select either $I_0$ or $I_2$, if $I_0$ is selcted then output = $A\overline{D}$ and if $I_2$ is selected then output = $\overline{A}D$, but which one is chosen depends on value of $D$. So we say $f = A\overline{D} + \overline{A}D$ (either $I_0$ or $I_2$), but which one exactly depends on $D$.

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okay i got! Thanks. All this time i was ignoring the fact that when D is 1  I2 will be selected. :p My bad.

Answer 2

output of mux 1 is

~A~B+~AB= ~A(~B+B)=~A=X1(NEXT TWO SELECT LINES HAVE 0 INPUT) THIS IS INPUT TO MUX2

~D~0.A+D~0.X1==>~DA+D~A

OUTPUT IS D XOR A

Answer 3

A'D+AD'