Question $2(10$ points$)$

The correct Boolean expression for the circuit below is:

Neither answer is correct

$x=A^{\text{'}}+B(C{D}^{\text{'}})$

$x=A^{\text{'}}B(C+D^{\text{'}})$

$x=$ABC$+D^{\text{'}}$

Question $3(10$ points$)$

Which of the following rules states that if one input of an AND gate is always $1,$ the

output is equal to the other input?

$A*1=A$

$A*A=A$

$A+A=A$

$A+1=1$

Question $4(10$ points$)$

Which of the following is not a valid rule of Boolean algebra?