i cannot understand

if we have a input signal such as X

we dont need to use inverter in the first input of the gates

can you explain why ?

 

X prime is just an inverted state of X, also called X not.

You dont need an inverter because the signal is inverted INSIDE the chip, rather than using an external chip.

 

Thanks but I didnt really understand. can you explain how to we do it.

 

Inside the IC, there is an inverter. It takes the input X and flips it to X not (also called X` or X prime) Prime just indicates its the opposite.

Example: If X=1, then X`=0. If X=0, then X`=1.