[-] SmartmanApps@programming.dev 0 points 1 year ago

I am not going to argue with you about it

Nor should you. I'm a Maths teacher.

This was resolved almost a month ago

And yet you still don't understand what's wrong with what you said.

Read the original equation again, plug some numbers into it, and try again.

That's what you need to do. You're the one coming up with wrong answers when you change the order. Changing the order doesn't change the answer.

If you still don’t get it I cannot help you

It's not me who doesn't get it. I teach it.

[-] SmartmanApps@programming.dev 0 points 1 year ago* (last edited 1 year ago)

The brackets are used to make the equation look cleaner

No, they're used to show deviations from the usual order of operations. If I want 2+3x4 to equal 20, then I have to write (2+3)x4.

10 - 1 + 1 = 8 doing the addition first

No it isn't. 10+1-1=11-1=10 is doing the addition first. Note same answer. You in fact did 10-(1+1) - you added brackets which changed the answer, thus a wrong answer

10 - 1 - 1 = 8 regardless of order because it is all subtraction

Not all of it. You're forgetting the 10 is really +10. -10-1-1 would be all subtraction. +10-1-1 is addition and subtraction.

it is not the same regardless of order

Yes it is! 😂 It is always the same regardless of order, as I have just shown you, again.

10-1+1=9+1=10

10+1-1=11-1=10

-1+1+10=0+10=10

1-1+10=0+10=10

1+10-1=11-1=10

-1+10+1=9+1=10

you do it left to right making it incorrect to do 1-1 first.

It's NOT incorrect to do 10-1+1 or 10+1-1. It IS incorrect to do 10-(1+1), which is what you did

By doing it out of order and incorrectly I was able to make my statement true

It was solely because you did it incorrectly. Order doesn't change anything.

[-] SmartmanApps@programming.dev 0 points 1 year ago* (last edited 1 year ago)

Another common issue is thinking “parentheses go first”

There's no "think" - it's an absolute rule.

then beginning by solving the operation beside them

a(b) isn't an operation - it's a Product. a(b)=(axb) per The Distributive Law.

(mostly multiplication)

NOT Multiplication, a Product/Term.

The point being that what’s inside the parentheses goes first, not what’s beside them

Nope, it's the WHOLE Bracketed Term. a/bxc=ac/b, but a/b( c )=a/(bxc). Inside is only a "rule" in Elementary School, when there isn't ANYTHING next to them (students aren't taught this until High School, in Algebra), and it's not even really a rule then, it's just that there isn't anything ELSE involved in the Brackets step than what is inside (since they're never given anything on the outside).

[-] SmartmanApps@programming.dev 0 points 1 year ago

Oh, but of course the statement changes if you add parentheses

It sure does, but they don't seem to understand that.

[-] SmartmanApps@programming.dev 0 points 1 year ago

Except it does matter

No it doesn't. You disobeying the rules and getting lots of wrong answers in your examples doesn't change that.

I left some examples for another post with multiplication and division

Which you did wrong.

I’ll give you some addition and subtraction to see order matter with those operations as well

And I'll show you it doesn't matter when you do it correctly

Subtraction first: 1 + (2 - 3) + 4 1 + (-1) + 4 = 4

Nope. Right answer for wrong reason - you only co-incidentally got the answer right. -3+1+2+4=-3+7=4

Right to left: 1 + (2 - (3 + 4)) 1 + (2 - 7) 1 + (-5) = -4

Nope. 4-3+2+1=1+2+1=3+1=4

Edit: You can argue that, for example, the addition first could be (1 + 2) + (-3 + 4)

Or you could just do it correctly in the first place, always obeying Left Associativity and never adding Brackets

in my opinion that’s another ambiguous case

There aren't ANY ambiguous cases. In every case it's equal to 4. If you didn't get 4, then you made a mistake and got a wrong answer.

[-] SmartmanApps@programming.dev 0 points 1 year ago

Addition first: 9-4=5

Nope. Addition first is 9+3-1=12-1=11. You did 9-(1+3), incorrectly adding brackets and changing the answer (thus a wrong answer)

[-] SmartmanApps@programming.dev 0 points 1 year ago* (last edited 1 year ago)

The solution accepted anywhere but in the US school system range from “Bloody use parenthesis, then” over “Why is there more than one division in this formula why didn’t you re-arrange everything to be less confusing” to “50 Hertz, in base units, are 50s-1”.

No, the solution is learn the rules of Maths. You can find them in Maths textbooks, even in U.S. Maths textbooks.

so no actual mathematician, or other people using maths in earnest, use that kind of notation.

Yes we do, and it's what we teach students to do.

[-] SmartmanApps@programming.dev 0 points 1 year ago

It’s so we don’t have to spam brackets everywhere

No it isn't. The order of operations rules were around for several centuries before we even started using Brackets in Maths.

((((((9+2)-1)+6)-4)+7)-3)+5

It was literally never written like that

we only need parentheses when we want to deviate from the norm

That has always been the case

[-] SmartmanApps@programming.dev 0 points 1 year ago

100% with you. “Left to right” as far as I can tell only exists to make otherwise “unsolvable” problems a kind of official solution

It's not a rule, it's a convention, and it exists so as to avoid making mistakes with signs, mistakes you made in almost every example you gave where you disobeyed left to right.

[-] SmartmanApps@programming.dev 0 points 1 year ago

until the ambiguity is removed

There isn't any ambiguity.

all those answers are correct

No, only 1 answer is correct, and all the others are wrong.

Until the author gives me clarity then that sentence has multiple meanings. With math

Maths isn't English and doesn't have multiple meanings. It has rules. Obey the rules and you always get the right answer.

it doesn’t click for people that the equation is incomplete.

It isn't incomplete.

[-] SmartmanApps@programming.dev 0 points 1 year ago

I stand corrected

No, you weren't. Most of their answers were wrong. You were right. See my reply. 4 is the only correct answer, and if you don't get 4 then you did something wrong, as they did repeatedly (kept adding brackets and thus changing the Associativity).

[-] SmartmanApps@programming.dev 0 points 1 year ago

Right to left:

6 * (4 / (2 * (3 / 9)))

Nope! 6 × 4 ÷ 2 × 3 ÷ 9 =4 right to left is 6 ÷ 9 x 3 ÷ 2 × 4 =4. You disobeyed the rule of Left Associativity, and your answer is wrong

Multiplication first: (6 * 4) / (2 * 3) / 9

Also nope. Multiplication first is 6 x 4 x 3 ÷ 2 ÷ 9 =4

Left first: (24 / 6) / 9

Still nope. 6 × 4 x 3 ÷ 2 ÷ 9 =4

Right side first: 24 / (6 / 9)

Still nope. 6 × 4 x 3 ÷ 9 ÷ 2 =4

And finally division first: 6 * (4 / 2) * (3 / 9)

And finally still nope. 6 ÷ 9 ÷ 2 x 4 x 3 =4

Hint: note that I never once added any brackets. You did, hence your multiple wrong answers.

It’s ambiguous which one of these is correct

No it isn't. Only 4 is correct, as I have just shown repeatedly.

Hence the best method we have for “correct” is left to right

It's because students don't make mistakes with signs if you don't change the order. I just showed you can still get the correct answer with different orders, but you have to make sure you obey Left Associativity at every step.

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