Truth table to equation question (comp Sci)

[dancingmaple]

Homework Statement

http://imgur.com/BSntip0

The Attempt at a Solution

for part a, i got the solution to be F1 = xy'+x'y= x⊕y (XOR) , F2 = x .y (AND)

for part b i don't understand how i would derive an equal equation that uses only NAND which is (xy') and inverter which is x'

 

[LCKurtz]

You can start by implememting xy' and x'y with AND gates and their sum with an OR gate. So you have two ANDS feeding an OR. Now on each line connecting an AND with the OR, put two bubbles, one on the AND output and the other on the OR input. The two bubbles are cancelling inverters, but they make the ANDS into NANDS and you have an OR gate with inverted inputs. What does DeMorgan's law tell you that makes?