(a) F(A,B,C,D)=(AB)'(C+D')
CIRCUIT DIAGRAM (4 inputs, 1 output)
(In these diagrams the logic gate numbers have no significance in relation to the question.)
(b) F(A,B,C)=AB'+A'B+CB (3 inputs, 1 output)
CIRCUIT DIAGRAM
(c) F(A,B,C,D)=(A'+B')'+C'D'+CD (4 inputs, 1 output)
(A'+B')'+C'D'+CD is the same as (A'+B')'+CD+C'D')
CIRCUIT DIAGRAM
(d) F(A,B,C)=((A+B)'(A'+B))' (3 inputs, 2 outputs)
CIRCUIT DIAGRAM
System size limitations have caused me to revise the presentation of this solution, so truth tables for each part of the question have been prepared as a single unit, shown below. (Signal convention is 1=ON, 0=OFF for the inputs and outputs.)