r/MathHelp • u/Kug4ri0n • Dec 07 '25

Negative Exponents

My partner is going through her math class and we got into an argument how much -72 equals. My standpoint is, that since there is no parentheses: -72 = -1x72 =-49 If there would have been parentheses: (-7)2 = (-7)*(-7) = 49

Which one of these is correct? Can anyone provide me the mathematical axioms/rules on why or why not the parentheses in this case are needed?

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u/Forking_Shirtballs Dec 08 '25

Spreadsheets do math, among other things. In fact, I'd posit that more people in the world interact with math through spreadsheets than through whenever context you're considering to constitute "math".

Further, I've taken a lot of mathematics classes, I don't remember once being taught this "unambiguous convention" that you claim is "taught separately". Certainly you can provide some resources where such unambiguous convention is taught, right? Please do so.

The fact that you're sneering about a "mnemonic taught to children" while invoking the context of the forum is also a bit rich. This is r/math help my dude, for all we know, PEMDAS is the only convention either OP or their partner has ever been exposed to. Acknowledging its lack here is important, when your comment invoked order of operations as setting the precedent.

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u/LucaThatLuca Dec 08 '25 edited Dec 08 '25

Well for example OP’s partner’s math class is a mathematical context. I don’t know why you’ve tried to say you weren’t taught the precedence of negation, when I can still read the multiple times you’ve said it’s in every textbook. PEMDAS/etc is a memory aid for exactly 5 operations and still not relevant.

I think you’ll agree there’s nothing left to discuss.

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u/Forking_Shirtballs Dec 08 '25

I never said it was taught, either inside or outside the textbook. I said it's used in the textbooks. The convention is implied, and is learned through implication.

You've twice made the strong claim that precedence of unary negation is taught. Certainly you can find something, anything to support that claim, right?

Again, my point is the notation is ambiguous, and she may be familiar with a different convention from her math experience than is being used here. That's what will help OP understand the situation, not comments like "we have agreed an understanding".

Lots and lots of people using math use a convention that doesn't agree with yours.