Noun + de/a + verb

Noun + de/a + verb
 

This is something that's confused me for a while, if I wanted to say 'easy to use' it seems like there are 3 options:

fácil usar
fácil a usar
fácil de usar

I think it's the last one but I'm not sure why, can anyone explain the difference between these?

thanks.

It is fácil de usar
fácil de entender = easy to understand :)

Fácil usar: es muy fácil usar la plancha.
Fácil de usar: la plancha es muy fácil de usar.
Fácil a usar :bad:

:)

Thanks for the help, could you give me some examples of when you do use a + verb?

I know you can say something like 'voy a hablar' but I still don't totally understand why the a is needed and you can't say 'voy hablar'.

This site may be of some help.

Rusty has hit the nail on the head. By convention or historical reasons, certain prepositions are used with certain nouns and verbs.

Thanks for the help guys.