>you say
>
>?5-2^2
>
>different than
>
>?-2^2+5
>
>that can't acceptable...

Metin - those are not equivalent expressions. You are confusing subtraction with negation... while they are somewhat interchangeable it isn't "commutative"

5 - 2 = -2 + 5

5 - 2^2 = -(2^2) + 5