Incorrect. By putting -5² you are signifying that the minus sign is the operator. Whereas if you put (-5)², you would be swapping it so that the minus sign is to create a negative 5.

You only need to put brackets around a negative number if it might otherwise be a bit confusing:

-5 - -8 looks a bit easier to read as -5 - (-8)

If there is no potential for confusion then the brackets can be dispensed with. -5² is, completely unambiguously, 'negative five to the power of two'. It is an error to read it as 'zero minus 5 to the power of two'. If you want to write the latter, then write 0 - 5²

The potential for confusion comes from using the same symbol to mean two very different things: the operation 'minus' and the sign 'negative'.

edit: Well, it looks like you have a supporter, at least as far as using the brackets is concerned

http://mathforum.org/library/drmath/view/55713.htmlIt's interesting, I have never come across a situation where -5² would be interpreted as anything other than 'negative five to the power of two'. I'm going to ask a few colleagues to see how they would interpret it.