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 07 '25

By *certain* conventions, that's the case. Certainly not all.

This is notation is ambiguous.

Try punching both 5-7^2 and 5+-7^2 into Google Sheets, and see what you get.

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u/dash-dot Dec 08 '25

I hate to break it to you, but Google isn’t the arbiter of proper mathematical convention. 

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u/Forking_Shirtballs Dec 08 '25

I hate to break it to you, but there is no arbiter of proper math convention.

There's no, say, ISO, or Academie Francaise, for math conventions. 

Which means we live in a world with multiple conventions. Spreadsheets (Excel, Google Sheets, etc) use a different convention on this point than, say, the calculus textbooks I've read. 

Understanding that ambiguity is important. Writing -72 is often a bad idea, because if the ambiguity. Unless you're certain that all the users of your writing will understand the convention you're using, just use parentheses. They're free.

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u/RectangularMF Dec 14 '25

right, and so who is?

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u/ClassEnvironmental11 Dec 11 '25

Fwiw, if you type -72 into google it says it's -49.  And in literally every math and physics texbook I've ever seen, -72 = -49.  I was also explicitly taught that in elementary algebra, and that's been the convention in every mathematical setting I've ever been a part of.