2-1 multiplexer using only nands and nots

[mathrocks]

I need to make a 2-1 mux using only NANDS and inverters. I thought it would look like a simple nand gate with another inverter attached at the end (basically a AND gate). However, that didnt work. I need it so when the selection input is a zero it selects whatever X0 is and when the selection input is a 1 it will always select 0. I know how implement it using 3 NAND gates and an inverter. But I thought since one input is constantly grounded, there would be a alot simplifed version.

Thanks

[dduardo]

When you try and figure out these problems it is always best to write out the truth table and solve the 3 variable k-map (for this case).

Hint: If the output of the MUX is X0 when S = 0 and the output of the MUX is 0 when S=1, then you'll need 2 inverters and 1 NAND.