4. (8 points)           

C*(A+B+!(!C+!D))*D 

   Distribution : distributed both C and D

A*C*D + B*C*D + !(!C+!D)*C*D

   DeMorgan

A*C*D + B*C*D + !!(C*D)*C*D

   Cancellation

A*C*D + B*C*D + C*D*C*D

   IdemPotent

A*C*D + B*C*D + C*D

   Identity

A*C*D + B*C*D + 1*C*D

   Distribution

(A+B+1)*C*D

   Null

1*C*D

  Identity

C*D

5. (4 points)            

!A+A*!B 

  Distribution

(!A+A)*(!A+!B)

  Inverse

(1)*(!A+!B)

  Identity

(!A+!B)

  DeMorgan

!(A*B)