Translation:The computer is very useful at my work.
Is there any difference between "pożyteczny," "użyteczny," and "przydatny?"
Those are pretty much synonyms. „Pożyteczny” is favored when talking about living organism, „przydatny” for objects and is most common of the three, and „użyteczny” is the rarest of three.
sjp.pl is also good for verifying whether the word is listed in at least one of the few chosen dictionaries and also give you the list of inflections, but many words are not defined and the inflections are not categorized in human-readable way. It's auto-generated for use in Scrabble-like game.
dobryslownik.pl is also a work in progress (and new words are included by subscribers' request). In its free version it can show you even some "controversial" forms like „póki co” or „Gienek”.
miejski.pl is basically Polish version of Urban Dictionary
pl.wiktionary.org can give you full inflections and definitions for some words, as long as you trust the userbase
That's probably because it's still a work-in-progress.
IIRC, they plan to finish that dictionary by 2020, so don't feel discouraged if you don't find something there until then – just check another dictionary instead. ;)
In fact, I was trying to find the etymology of "przydatny"; in the end, I found "przydać się" in my paper (!) Wielki Słownik Pol. to Eng. by Oxford/PWN. I was just curious as to how the verb "to give" gets into an adjective meaning "useful".
And how does the verb "to give", when accompanied by "up" means "to resign"?
Such stuff is kinda hard to explain, except that it simply changes the meaning in specific ways.
The English answer with "useful at my job" reads very strangely. Perhaps "useful at my work" or "useful in my job". Probably need a Polish person to choose
The problem with 'at my work' is that it assumes a relationship between the computer and the work, while the computer is a part of the work itself. Hence in my job and in my work.