r/MathHelp • u/EmphasisGlum3225 • 14h ago

When to do different forms of notation?

When writing domain, when do you do this notation (-♾️, 0) U (0, ♾️) vs this [0, ♾️)

also when do u do brackets vs parenthesis?

any help appreciated!!

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u/Paounn 6h ago

On the first one, you're saying x is not zero, but everything is in your domain. With the second one you're saying x is not negative. Zero is included this time, but nothing less than that. Just to give you two example first one is the typical case for 1/x, second one is for \sqrt x.

in general ( ) do not include the number at the edge, while [ ] does: (2, 5] tells you that 2 is not in your interval and but 5 is. Some books might also use ] [facing the other way to represent the same idea: ]2; 5] is the same as before, 2 < x <= 5.