what is the rule in adding rational numbers
The rule in this case is that there are no numbers in any position.
To guess a rule for a pattern, you need several numbers, not just one. Of course, you can invent any rule, for example, "all numbers in the sequence are equal to -4", or some more complicated rule.
If it were not true, it would not have become the rule!
Opposite numbers rule
they mean that they are numbers of or to pertaining to the numbers on the product. Identifiers.
what is the rule in adding rational numbers
The rule in this case is that there are no numbers in any position.
Of or pertaining to a series; consisting of a series; appearing in successive parts or numbers; as, a serial work or publication., Of or pertaining to rows., A publication appearing in a series or succession of part; a tale, or other writing, published in successive numbers of a periodical.
It IS (still is, not was) (basically) the rule book of Judaism as written by Rabbis, pertaining to laws, ethics, customs, and history.
To guess a rule for a pattern, you need several numbers, not just one. Of course, you can invent any rule, for example, "all numbers in the sequence are equal to -4", or some more complicated rule.
If it were not true, it would not have become the rule!
Pythagoras
Never.
The rule method is used to describe any set of numbers, so put any sequence of numbers in brackets and there you go.
Opposite numbers rule
Since a given sequence of numbers can be designed to follow any rule, you have to use a system of trial and error to see if you can discover the rule. Sometimes the rule is obvious, sometimes it is extremely complicated. Try to invent a rule which would produce the sequence that you observe.