[Tex/LaTex] For formal articles, should a displayed equation be followed by a punctuation to conform to the language grammar

equationsgrammar

For formal articles, should a displayed equation be followed by a punctuation to conform to the language grammar ?

For example:

The most well-known physics formula is

$E=mc^2.$ %should I put a period here?

And if you expand

$(x+y)^2,$ % should I put a comma here?

you will ...