I tried messing with Demorgan's theorem and some other tricks and tips but i just can't get this part of the problem it gives me the Diagram for;

F= ((N3' N2' N1' N0')+(N3' N2' N1' N0)+(N3' N2' N1 N0')+(N3' N2' N1 N0)+(N3' N2 N1' N0'))';

Part 1- was to write out f as a function of boolean variables N3-0 (Done)

Part 2- Write the above boolean function in SOP form
This is the part where i have no idea what to do demorgan's and other stuff just isnt working for me.

Part 3- Give a truth Table (Done)

Part 4- Use A k-map to simplify the obtained expression in part2 and draw the circuit. (Done- my simplified equation id F= N3+N2 N1+N2 N0, is that the SOP form he wanted in part 2?)

Part 5- Draw the circuit using only 2-input NAND gates (Done)


Any help is appreciated greatly

 

Have you read this:
http://www.allaboutcircuits.com/vol_4/chpt_7/8.html

Watch this video too:
http://www.allaboutcircuits.com/videos/87.html

 

The solution of a K-map by grouping the 1s is always a Sum of Products.

 

Apply Demorgan's on it twice, once on the whole thing and once for each of the 5 pieces. Doing that I got the same simplification you did.