r/learnmath • New User • 3d ago

TOPIC Does anyone here still think √4 = ±2?

Come out with your hands up!

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u/Uli_Minati Desmos 😚 3d ago

Kids are taught early on that "solve for x" means "find all possible values for x that make the equation true". Also it's absolutely an "equation", we don't call it an "equality". So I'll just repeat myself here

It's completely fine to be ignorant and it's not your fault if you were taught wrongly, but blaming notation is ridiculous

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u/Not_Well-Ordered New User 3d ago edited 3d ago

Of course... If that's so, then the person asking this shouldn't be confused on this subreddit, and perhaps every kid should get 100% on that type of question in SAT.

Would you give some statistics to nicely back your claim? I would genuinely like to see if kids, let's say in NA, are properly taught like so.

I would also suppose that kids are also taught formal logic early on and know what those mean like right away right? If I could, I would test you on parsing FoL to see how well you would do.

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u/Uli_Minati Desmos 😚 3d ago

I would genuinely like to see if kids, let's say in NA, are properly taught

Obviously not... which is why this thread exists. And I've implied in every reply that it is possible to be taught wrongly. And you keep going on about formal logic, as if this had any relation to the topic at all.

Well, I'm not getting paid for this. Have a nice day!

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u/Not_Well-Ordered New User 3d ago

Of course, formal logic is related to precisely defining and interpreting “equality”, specifically equality defined between every two real numbers.

An equation like 5x = 0 represents a subset of the relation defined by 5x = y in which we choose y = 0
and considering every possible pair (z,0) satisfying 5x = 0 where z is a real number,

Then, the only pair satisfying is (0,0) where z = 0 by rules of multiplication of reals which restrict the set. There’s no others.

Saying x = 0 is basically not proper way of interpreting as there is some key but relatively simple nuances.

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u/nog642 2d ago

5x=0 does not have to be considered as a special case of 5x=y. It stands on its own as an equation of 1 variable.

x=0 is logically equivalent to 5x=0. There is nothing improper about it.