In article <sYTPc.1888$Uh.1172@fed1read02, "KeithK"
wrote:

I doubt that any U.S school, including yours, teaches a different convention
-z is the negation of z.

Of course not. Nobody is disputing that...

With z=x^2 you have -x^2 is the negation of x^2

And of course you know that the second statement doesn't logically
follow from the first. Nor is it logically incorrect. It's simply an
assertion.

Doubt if you must, but the US high school I attended used the opposite
to the supposedly "universal" convention (though it was certainly
discussed as a convention, not "the universal truth", and I'm fluid
enough to accommodate whichever convention(s) are being used).

Since a significant portion of the curriculum for the Calc and DiffEQ
courses (algebra was 7th grade) included daily exercises on the material
using APL (as did my college math courses), that was, perhaps, a natural
consequence. It certainly emphasized the difference between negation and
subtraction, and the *formality* of order of precedence was made more
salient.

Typographically, the negation operator in our textbooks was different
than the subtraction operator, and parentheses were used when needed.

I no longer know what curriculum is used at that school, of course,
though at least one of the faculty members that taught me is still
there. Might be diverting to give her a call...