Why does the expression -a does not always represent a negative number?

Answer 1

* If "a" is positive, "-a" is negative.* If "a" is negative, "-a" is positive.

* If "a" is zero, "-a" is zero.

If you want to force a negative number, you can write -|a|, i.e., the negative of the absolute value.

Answer 2

The expression -a does not always represent a negative number because could be negative changing the negative sign in front to a positive sign.