Why does BIDMAS not always apply to squaring negative numbers?

[AlfieD]

Furthermore, in general, if you have an equation with some "x", when you put a value in it, you should always put parenthesis around it, because otherwise you can lose any meaning of x if x itself contains operations.

For example, if I have $2x + x^{2}$ and I want to replace x with "y + z," the way to do that is to write $2(y + z) + (y + z)^{2}$. If I don't put those parenthesis for the first term, I am not doubling x, or y + z, I am doubling y and then adding z afterwards, and a similar problem arises for the second term.

Yeah, awesome, I understand that.

 

[Borek]

But if you substitute $x$ for it's value of -1, so $x$² would become -1², which would be -1. Or does it not go to that when you change it?

I told you to use parentheses. Then x² for x=-1 becomes (-1)² and there is no ambiguity.

Besides, linking here to another thread you started two separate discussions on the same subject. It always means mess. I am locking this thread.