ok so I am asked to implement the following boolean function: F(w,x,y) with these minterms (0,2,3,5). I am allowed to use a single decoder(74138) and a single nand gate. I found the solution using De Morgan's laws of logic but it seems like I need inverters for the minterms 0,2,3,5. Please help me...

thank you...

 

As usual, you need to show YOUR attempt to solve YOUR homework problem. Then we can look at what you've done and where you need to go and make suggestions that will hopefully steer you down that path.

 

ok my solution is like this: I have one 3x8 decoder with bubbles on each output and 0,2,3,5 connected together to a single NAND gate. This is right I've tested it however the task is like this: "Implement F with a single decoder and a single NAND gate".

 

The title ... using a single 8:3 decoder
But you using 74138, that is 3:8 decoder, does some mistake of the title?

 

ok my solution is like this: I have one 3x8 decoder with bubbles on each output and 0,2,3,5 connected together to a single NAND gate. This is right I've tested it however the task is like this: "Implement F with a single decoder and a single NAND gate".

You have the right idea. When you say that you've tested it, how did you test it? In simulation or with the real IC? If in simulation, did you use the model for the 74138 specifically, or just a generic 3:8 decoder?

Go look at the datasheet for the 74138 and I think you'll see your problem and how to fix it.