$+(+x) = +x$
but why is $-(-x) = +x$???
What's the reason behind the rule, it's really basic and "obvious" because a no turns a no to a yes
But I don't want to reason like that, lol. So how would you explain it? Do I just say on a real number line $-x$ makes a turnaround and $-(-x)$ would turn it positive again?
Also if I say for example: $-x = 5$ then I do have $-(-x) = -5$ Is it correct? It wouldn't matter, right?
(Btw: I don't know if the tag "elementary-number-theory" is correct)
**The question is different to $(-x)*(-x)=x$