LaTex is for typesetting. I know of nobody who "does the math" in LaTex; they do the math on paper and write it up in LaTex for presentation or publication (or if they need to ask a question on MathOverflow, or something like that).
That said, you should learn LaTex if you ever want to do research in anything mathematical.
I totally do some math in latex :). It's just easier to convert mentally sometimes than get paper out.
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