My Math Forum Order of operation

 Elementary Math Fractions, Percentages, Word Problems, Equations, Inequations, Factorization, Expansion

 September 22nd, 2019, 10:13 AM #1 Newbie   Joined: Sep 2019 From: Poland Posts: 3 Thanks: 0 Order of operation My daughter has a math problem that both me and my wife got incorrect due to order of operations. The problem is: (2 3/4 - 3.5) * (-2^2) Solving each term between the brackets = (11/4 - 14/4) * (4) = (-3/4) * (4) = - 12/4 = - 3. The correct answer and method according to the key is as follows.... (-3/4) * (-2^2) = (3/4) * (2^2) = 3..... What is this black magic where you are allowed to multiply each term between brackets by - 1 before raising - 2 to the powers of 2? Shouldn't powers go before multiplication? Help would be appreciated!
 September 22nd, 2019, 10:33 AM #2 Senior Member   Joined: Jun 2019 From: USA Posts: 310 Thanks: 162 We had a discussion about this several weeks ago. I think the consensus was that by convention, -2^2 without brackets does not mean (negative two) squared, but the negative of (two squared). The same as $\displaystyle e^{-x^2}$ means $\displaystyle \frac{1}{e^{x^2}}$. Incidentally, I was in the camp that initially thought the same as you. Thanks from topsquark and Dropjesijs
 September 22nd, 2019, 10:49 AM #3 Newbie   Joined: Sep 2019 From: Poland Posts: 3 Thanks: 0 The fun of it is that if you type it out in python you get 3. If you put it into open office calc you get - 3. So that could cause a lot of damage ðŸ˜• Since renown software gives different answers I'm not sure how mere mortals should treat this... Thanks for the answer though. It's appreciated
 September 22nd, 2019, 11:08 AM #4 Senior Member   Joined: Mar 2015 From: Universe 2.71828i3.14159 Posts: 132 Thanks: 49 Math Focus: Area of Circle Which means developers of Python are smarter. Although OpenOffice may have been developed in Python, I am not sure.
 September 22nd, 2019, 11:13 AM #5 Senior Member   Joined: Jun 2019 From: USA Posts: 310 Thanks: 162 Someone went to the trouble of performing a survey of various coding languages' interpretations, and basically the conclusion was: when in doubt, use brackets.
September 22nd, 2019, 11:22 AM   #6
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Joined: Sep 2019
From: Poland

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Quote:
 Originally Posted by DarnItJimImAnEngineer Someone went to the trouble of performing a survey of various coding languages' interpretations, and basically the conclusion was: when in doubt, use brackets.
Agreed... However in this case I was never in doubt. So yes... That's a bit scary...
Also I deal with a lot of rules and regulations.. That are written in that form.

How am I to know in what camp the regulator was when writing the rules....

Really scary stuff...

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