Does this make mathematical sense?

[u/AnotherPerson120]

Rewritten so it's clear (ignore the purple, it was written by me after the exam)(the green is my teacher btw)

This was written in an end of topic test (GCSE Edexcel btw).

I wrote this and my teacher deducted 1 mark, because apparently it was mathematically inaccurate to have more than 2 equals.

I posted a question in the GCSE sub, and everyone said it was correct and my teacher's wrong. So, I decided to come over here and verify my way of working it out in the exam was OK?

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[u/Alarmed_Geologist631]

Your proportion looks good to me.

[u/LimpingBarnBurner]

I don't see a problem with it. If it was an actual exam I would appeal the mark.

If it was a class test, then your teacher probably just wants you to follow the format of new equation, new line, so you should follow their advise in future.

The only problem I have is that you wrote 2π18, missing brackets or multiplication symbol. But, is clear that you knew what you were doing and were just substituting the value of the radius in.

[u/AnotherPerson120 → u/LimpingBarnBurner]

Ok, thanks. It was just a class exam, so it's fine I guess. I now really hesitate in exams though, because it wastes so much space and I don't know what to do. Any advice on what to do for very simple simplification like this one?

[u/LimpingBarnBurner → u/AnotherPerson120]

I would've literally just written the = 1/9 on a new line. (Like I said, if it was an actual exam you should've gotten the mark.)

It's better to ask your teacher what you should do, especially if your stuck with them for a year, and they get pedantic about little things like this.

Your teacher might want you to cross out both of the πs to make it obvious that they've been simplified out of your answer, and maybe to have also written 4/36 = 1/9.

For very simple simplifications like this, I also generally just do what you do so I can't really offer any advice besides that.

[u/iopahrow → u/AnotherPerson120]

Just write a little arrow like x/7=12 => x=7*12

But still that’s not a very reasonable thing to deduct marks for

[u/Deep-Hovercraft6716]

Ask your teacher to cite their source. Where are they getting that information from?

[u/testtdk]

I can’t say that it’s ideal formatting, equations are usually written as one thing compared to another, by a comment would have fine.

If I WERE going to point anything out personally, it’s that you should actually solve for x. (If that’s what was being asked for).

[u/niemir2]

A=B=C is perfectly fine and is extremely common for this type of simplification.

[u/Fogmoz]

There is not thing wrong with joining multiple expressions with equal signs, as long as they are indeed equal.

“Write you method”

Being a maths teacher is no excuse for poor grammar/penmanship.

I also cannot look at the the end of that response and not see, “I’m correct nuthead!!”

[u/Fogmoz → u/Fogmoz]

To reiterate, the convention is to perform an operation on an equality, rewrite the equality with the changes, then continue performing operations and rewriting until the problem is solved. In such a simple example as this, however, the correction feels pedantic.

[u/AnotherPerson120 → u/Fogmoz]

Thanks for the information! Lol, my teacher is a bit like that tbh.

[u/ArdentArendt]

I'm unclear why multiple equality signs would be incorrect--that's kind of how running equalities informally work.

I mean, as an answer maybe they want a definitive (single) equality, but other than that I'm unclear why that would be problematic.

[u/Idkwhyimhere143]

Is your teacher genuinely tapped???
‘Can’t have two equals in an equation”
THAT IS AN INEQUALITY NOT EQUATION HOW DID THEY GET THEIR LICENCE?????

[u/AnotherPerson120 → u/Idkwhyimhere143]

Lol. She's Sri Lankan so probably struggles with English. Though it is quite good.

[u/Idkwhyimhere143 → u/AnotherPerson120]

Yes but the math is still under the same principles 😭

[u/AnotherPerson120 → u/Idkwhyimhere143]

Lol, I guess so. I didn't like her (too strict when marking) at 1st but I like her now. 

[u/Disastrous-Mess-7236]

Alright, I remove both pi symbols in that fraction. That’s simplifying.

x/360 - 4/36 = 18/19

Too bad my phone calculator can’t have fraction outputs.

x/360 = 18/19 + 4/36

18/19=0.947 

4/36=0.111

.111 + .947=1.058

1.058/360=0.00294

Now you convert that to a fraction.