Infinite, just like 0, actually has no - or +. So yes and no. For all intents and purposes -inf == inf.
This is completely wrong, please don’t listen to this person.
I suggest you Google “Projectively Extended Real Numbers”.
You mean this one?
The projectively extended real number line is distinct from the affinely extended real number line, in which +∞ and −∞ are distinct.
Now tell me, do we usually work with the projectively extended real numbers?
One positive infinity doesn’t even necessarily equal another positive infinity, as two expressions might not approach infinity at the same rate. Note the word “approach”. That’s the only way you’re allowed to use infinity/-infinity, by approaching it. It’s not a real number, it doesn’t actually exist. Second, in most contexts (calculus) it strictly refers to magnitude (ie, it can have directionality applied to it). Take a calculus class if you want to learn more.
