does 2u maths still count towards my atar? (1 Viewer)

[cutemouse]

Sorry, what cases?

Open your eyes:

infinity/infinity , 0/0, infinity - infinity or 0*infinity

 

[ilikebeeef]

Open your eyes:

I can't see cos I'm blind argh where's my blind-man-stickkk JKS

According to this: What does Infinity Divided by Infinity Equal? Phil for Humanity

infinity/infinity is undefined.
0/0 is indeterminate.
infinity-infinity is undefined.
0*infinity is undefined.

2/0 is undefined.

 

[frenzal_dude]

Ohhh... so BASIC questions huh...

Then find:




Look in the Coroneos 2U book. There's a good explanation there in the limits chapter.

is the answer 1/5?

 

[cutemouse]

I can't see cos I'm blind argh where's my blind-man-stickkk JKS

According to this: What does Infinity Divided by Infinity Equal? � Phil for Humanity

infinity/infinity is undefined.
0/0 is indeterminate.
infinity-infinity is undefined.
0*infinity is undefined.

2/0 is undefined.

Lmao, "Phil for humanity"...

is the answer 1/5?

Yes. But according to our friend Anna's 'theory', it would've been 1

 

[annabackwards]

Lmao, "Phil for humanity"...


Yes. But according to our friend Anna's 'theory', it would've been 1

No, it would've been 1/5 if i did it the HSC way

Even with my way that you won't drop (please, go out some more) it'd be 1/5 as you'd factorise the 5 out of the bottom and cancel down the infinity/infinity.

 

[cutemouse]

No, it would've been 1/5 if i did it the HSC way

Even with my way that you won't drop (please, go out some more) it'd be 1/5 as you'd factorise the 5 out of the bottom and cancel down the infinity/infinity.

Make up your mind Anna.

 

[Trebla]

"Undefined" usually means that it doesn't converge to a certain number at all. For example, "1/0" is undefined because when x approaches 0 for 1/x there is no convergence (i.e. it blows up to infinity which has no defined position on the number line)

"Indeterminate" usually means that it is POSSIBLE to have convergence under certain specific contexts (which is yet to be determined). This means that limit may exist under certain circumstances. For example, "0/0" is indeterminate because it is possible that it may converge to a defined value when you let the numerator and denominator both approach zero.

For example, say we have x approaches zero for (sin x)/x. If you sloppily 'sub' the x = 0, you get "0/0" BUT from trig functions you should know that sin x approaches zero at a very similar rate that x approaches zero (sin x ~ x if x is sufficiently small), hence it is actually well defined.

However in a different context "0/0" may actually be undefined. For example, let x approach zero for x/x². If you sloppily 'sub' the x = 0, you get "0/0" BUT the x squared term in the denominator dominates over the linear x when it comes to shrinking it very small. Therefore, the denominator will be much smaller than the numerator as x approaches zero, hence the expression overall blows up to infinity and becomes undefined.

 

[annabackwards]

Make up your mind Anna.

Note that my way is basically the HSC way.

Wow, you really can't take a well placed joke (unless you're joking too lol). Tis one of the reasons why you're gone from my msn list~

"Undefined" usually means that it doesn't converge to a certain number at all. For example, "1/0" is undefined because when x approaches 0 for 1/x there is no convergence (i.e. it blows up to infinity which has no defined position on the number line)

"Indeterminate" usually means that it is POSSIBLE to have convergence under certain specific contexts (which is yet to be determined). This means that limit may exist under certain circumstances. For example, "0/0" is indeterminate because it is possible that it may converge to a defined value when you let the numerator and denominator both approach zero.

For example, say we have x approaches zero for (sin x)/x. If you sloppily 'sub' the x = 0, you get "0/0" BUT from trig functions you should know that sin x approaches zero at a very similar rate that x approaches zero (sin x ~ x if x is sufficiently small), hence it is actually well defined.

However in a different context "0/0" may actually be undefined. For example, let x approach zero for x/x². If you sloppily 'sub' the x = 0, you get "0/0" BUT the x squared term in the denominator dominates over the linear x when it comes to shrinking it very small. Therefore, the denominator will be much smaller than the numerator as x approaches zero, hence the expression overall blows up to infinity and becomes undefined.

Oh i see. Thank you very much for explaining it so very clearly! There should be more teachers like you in the world

 

[hscishard]

I can see both sides. Can't we just say infinity isn't a number

 

[ilikebeeef]

I can see both sides. Can't we just say infinity isn't a number

Infinity is not a number.

 

[annabackwards]

Infinity is not a number.

Yeah, we got that drilled into us at uni XD

It's not a number, it's more a describing the concept of numbers continually increasing.

Infinity is only a number in the surreal set of numbers but even most uni courses don't explore the surreal set of numbers

 

[cutemouse]

Yeah, we got that drilled into us at uni XD

It's not a number, it's more a describing the concept of numbers continually increasing.

Infinity is only a number in the surreal set of numbers but even most uni courses don't explore the surreal set of numbers

You know what was really funny? The fact that the day after this 'argument', we had a lecture on limits which proved that I was right...

 

[annabackwards]

You know what was really funny? The fact that the day after this 'argument', we had a lecture on limits which proved that I was right...

You were using UNI maths to explain HSC concepts which didn't need the UNI maths to be solved. My way actually also proven correct for basic limits

OMG HSC =/= Uni? Are you kidding me? oO

 

[cutemouse]

You were using UNI maths to explain HSC concepts which didn't need the UNI maths to be solved. My way actually also proven correct for basic limits

OMG HSC =/= Uni? Are you kidding me? oO

Since when in the HSC infinity/infinity = 1 :S

And no, I was not using Uni maths to explain HSC concepts.

I'll say 'hi' to you soon though

 

[annabackwards]

Since when in the HSC infinity/infinity = 1 :S

And no, I was not using Uni maths to explain HSC concepts.

I'll say 'hi' to you soon though

infinity/infinity = 1 if the both the denominator and numerator are linear or can cancel down so that they are linear. If you take a look at your uni maths book, there are examples of different indeterminate examples including the linear ones which are used in the HSC.

You mocked my HSC way of doing things because it was "wrong" and used uni concepts to explain how i was wrong when those concepts agree with me.

LOLOLOLOLOLOL you are so weird =='

 

[hscishard]

Talking about weird but haven't you guys realised you've been fighting and everyones like...weirdos.

Just kidding. Prove your points!:uhhuh:

 

[cutemouse]

infinity/infinity = 1 if the both the denominator and numerator are linear or can cancel down so that they are linear.

Your 'theory' fails with something like (2x+1)/(x-1) even though both the denominator and numerator are linear.

If you take a look at your uni maths book, there are examples of different indeterminate examples including the linear ones which are used in the HSC.

Didn't you read above? I stated the 4 cases of indeterminant forms. I knew them when I was doing my HSC.

You mocked my HSC way of doing things because it was "wrong" and used uni concepts to explain how i was wrong when those concepts agree with me.

It was wrong because it clearly fails for stuff like (lnx)/x and the example above. You would mislead students by not teaching this properly.

For example, you know full well that the ASS test for congruency does not always work. Thus we do not use it. Why would you? It's like what you've said above, that infinity/infinity = 1. It can be 1 in some cases, but it isn't always. So we shouldn't use it.

 

[annabackwards]

Your 'theory' fails with something like (2x+1)/(x-1) even though both the denominator and numerator are linear.


Didn't you read above? I stated the 4 cases of indeterminant forms. I knew them when I was doing my HSC.


It was wrong because it clearly fails for stuff like (lnx)/x and the example above. You would mislead students by not teaching this properly.

For example, you know full well that the ASS test for congruency does not always work. Thus we do not use it. Why would you? It's like what you've said above, that infinity/infinity = 1. It can be 1 in some cases, but it isn't always. So we shouldn't use it.

No, it doesn't fail. If you look in your book it'd explain how'd you do it, how i would do it. Put in infinity so you'd get 2infinity/infinity, cancel down as according to my way linear infinity/infinity = 1 and you get 2.

That idea works fine for the HSC, as well as uni (do look in your booklet already ==').

(lnx)/x would be only given to 4U kids or at the very least 3U kids with guidance/specific steps on how to do it. My advice for 4U kids would be to sketch as usual and pick out the trend.

Hence, my way is valid - even the uni booklet says so. Oh and indeed, they are indeterminate forms but that is out of the HSC course - i'd rather not waste my time teaching them something they do not need to know to do the HSC question they will be expected to know how to solve.

ASS is not used - SAS is used as it always works for at the very least the HSC. My way/the uni's way works for all HSC limit questions which are basic and do not go into the depth that uni maths goes into hence it is used/taught.

 

[cutemouse]

No, it doesn't fail. If you look in your book it'd explain how'd you do it, how i would do it. Put in infinity so you'd get 2infinity/infinity, cancel down as according to my way linear infinity/infinity = 1 and you get 2.

That idea works fine for the HSC, as well as uni (do look in your booklet already ==').

The method employed is to factorise the fastest growing term in the denominator from both the numerator and denominator and cancel. Nothing that involves infinity/infinity.

(lnx)/x would be only given to 4U kids or at the very least 3U kids with guidance/specific steps on how to do it. My advice for 4U kids would be to sketch as usual and pick out the trend.

It could well be asked in a 2U exam. Although yes, it would more likely be asked in a 3U exam. So go figure. You'd be misleading students.

Furthermore, I think a question of this type would be too easy to be asked in a 4U exam (although, if they had more students like you then it'd be more likely that they ask it ;D).

All I'm saying is that your 'theory' is misleading.

Hence, my way is valid - even the uni booklet says so. Oh and indeed, they are indeterminate forms but that is out of the HSC course - i'd rather not waste my time teaching them something they do not need to know to do the HSC question they will be expected to know how to solve.

Well put it this way. It isn't that hard to learn and explains stuff properly. It's like in the current HSC Physics syllabus. It doesn't state that you need to know what a interference pattern is, but you should know it in order to enhance understanding in say, the MM project.

ASS is not used - SAS is used as it always works for at the very least the HSC.

AAS and SSS could also be used. But you've missed my point.

All I'm saying is that you should teach maths properly (ie. in a logical and systematic manner).

 

[annabackwards]

The method employed is to factorise the fastest growing term in the denominator from both the numerator and denominator and cancel. Nothing that involves infinity/infinity.

Yes i agree, but many students see the trend in the first place and as the booklet says, if x-->infinity and f(x) = x/x it approaches 1. Same deal if f(x) = x^2/x^2 etc etc.

It could well be asked in a 2U exam. Although yes, it would more likely be asked in a 3U exam. So go figure. You'd be misleading students.

Furthermore, I think a question of this type would be too easy to be asked in a 4U exam (although, if they had more students like you then it'd be more likely that they ask it ;D).

No, they wouldn't ask a 2U kid to sketch ln(x)/x unless they were literally being led through how to do it. Same deal with a 3U kid. They have asked it in a 3U exam, albeit it in the form of sketches rather than implicit finding the limit style questions.

All I'm saying is that your 'theory' is misleading.

My theory is not misleading, it's exactly just as the book says, i'm just skipping steps. And i was messing with you in the first place. How many times must i say this until it gets into your head? I wasn't even paying much attention to what you were saying at the time =='

Obviously when i teach i do not skip steps and teach the entire thing, step by step showing that the top and bottom are divided by the highest power in the denominator.

Well put it this way. It isn't that hard to learn and explains stuff properly. It's like in the current HSC Physics syllabus. It doesn't state that you need to know what a interference pattern is, but you should know it in order to enhance understanding in say, the MM project.

AAS and SSS could also be used. But you've missed my point.

All I'm saying is that you should teach maths properly (ie. in a logical and systematic manner).

No, your point was that you shouldn't use the ASS method to prove congruency as it never works - but my skipping the steps does always work. As if the top and bottom are to the same power, when you divide top and bottom by the highest power in the denominator it cancels down to 1.

Just take a look in the book, it even says so. Yes, infinity/infinity is indeterminate but iff the powers on the top and bottom are the same you end up with a limit of one.