Maybe is skewed. I was taught that -3^2=9, and not -9. The integer used
is -3, not -1*3. You may think I was taught wrong. I submit to you I was not
taught in this country, rather, I grew up in Europe. Could it be that Excel
had some European programmers....

This could have something to do with it.

However, the convention -x^2 == -(x^2) is not negotiable when you are
working with algebra. If you are dealing with real numbers, then writing -x^2
would be pointless if -x^2 really means (-x)^2 == ( -1)^2 * (x)^2 = x^2

Therefore, if the "European convention" you mention holds, then -x^2 == x^2.
(!)

So then, -x^2 should be taken as -(x^2), to mean the opposite of the square
of x, and to differentiate it from simplifying to x^2.

Cheers,
Peter

**PS**

The post that Alan mentioned (http://tinyurl.com/5t69s) is good reading on
this topic. Apparently the issue cost someone $2000 in time and effort to
resolve!

The convention as I've learnt it is that the power operator is only applied
to the argument immediately under the indice. So for instance:
2 * 3^2 = 2 * 9 = 18 AND
(2 * 3)^2 = 6^2 = 36
(2 * 3)^2 = 2^2 * 3 ^ 2 = 4 * 9 = 36

Therefore, if the negative is meant to be included in the power, it should
be included in brackets. So then:
-3^2 = -1 * 3^2 AND
(-3)^2 = 9
(-3)^2 = (-1 * 3)^2 = (-1)^2 * (3)^2 = 1 * 9 = 9