Mathematics Corner :)

[Yanal]

^ math hard I'm almost failing,and thats saying something.

 

[Banu_Hashim]

^^
Hahahaha...whatever you say!

 

[Yanal]

Sister Raynn ,what do you learn in A math? Are A levels in Canada?

 

[Banu_Hashim]

In the UK bro. You do it between the ages of 16-18

 

[~Raynn~]

Sister Raynn ,what do you learn in A math? Are A levels in Canada?

You do a little of everything in A-level math...more algebra, more geometry, lots and lots of calculus...and you have to do applied modules (in statistics or mechanics or something) too...

And yup, A levels are specific to the UK...hmm, I don't know about the system in Canada...

 

[Yanal]

Need help today! How do u do percent? Like 28% of 897? Please explain in simple words.

 

[Woodrow]

Need help today! How do u do percent? Like 28% of 897? Please explain in simple words.

First change the % to a decimal.

28%=.28

Now multiply 897 x .28


897
x.28
07176
17840
250.16

 

[Woodrow]

First change the % to a decimal.

28%=.28

Now multiply 897 x .28


897
x.28
07176
17840
250.16

Another way, which may be how your teacher is explaining it would be to multiply 897 x 28 and divide by 100

897 x 28= 25016


25016 divided by 100 =250.16

 

[Yanal]

JazakAllah how bout 70% of a number is 49.

 

[Woodrow]

JazakAllah how bout 70% of a number is 49.

This you do in the opposite order. However to avoid confusion I will use 20% of a number is 49.

20% means 20 parts per 100

divide 100 by 20

OOOOps20 divided by 100 that was supposed to be-- 100 divided by 20 = 5

49 is one part of the full 100% there are 5 parts to make 100%

Multiply 49 x 5 that equals 245 for your answer.

Now you try it with the 70% the answer will surprise you.

 

[Abdu-l-Majeed]

JazakAllah how bout 70% of a number is 49.

Always use a suitable notation. Writing down things can make the things very easy.

http://img142.imageshack.us/my.php?image=20090327130331.jpg

 

[transition?]

It's quite funny, I only started calculus in year 10..was about 14/15ish. When are you expected to start calculus in the states do you know?

I believe they start calculus your third or fourth(the last) year in high school. So I'd say mainly 16/17/18 ish. On that note, I'm surprised you started at 14/15!

It really depends though which math track you're on. Some people are quite blessed, they go on a faster track. Others don't touch a real calculus until they've graduate their fourth year in high school and gone to a university.

 

[transition?]

lol, on a good note, once you do get into higher level math, computers and these ginormous calculators do your triple integrals for you =) !!!

 

[~Raynn~]

^ Lol, exactly!

At present, we're doing this module entitled 'decision maths'...it basically involves using loads of different (usually pointless, and always ridiculously time-consuming) algorithms to, for example find the shortest path from one place to another, or match things together in the best way possible...and there's actually even an algorithm for putting numbers in ascending order, . As if any of this would ever be done by hand...

(And also - to add to the percentages stuff - yup, using the right notation makes everything so much easier. It's important to be able to change a worded question into an equation you can solve...like, where it says %, you write /100....and the word 'of' means multiply...so 28% of 897 is just 28/100 * 897, etc...)

 

[Mysterious Uk]

I'm doing a placement in a primary school and their way of subtraction has changed a lot since my day. They do it in the form of partitions and exchange so

67-39=

60-30 7-9 can't do that so you borrow 10 from 60 and add to 7 so..
50-30= 20 17-9= 8

20+8= 28 so 67-39= 28

This is a method used by year 3's or 7-8 year olds lol It is an interesting method lol thought i'd share it.

 

[The Ruler]

^I taught the gool ol' borrowing. My teacher, I remember, made each borrowing like one shopkeeper borrowing vegetables from the other. That was, I suppose, our first lesson in business and trade too.

 

[The Ruler]

Parametric differentiation:

- The parametric equations of a curve are x = asin t, y = a cos^2 t, 0</= t </=pi/2

I differentiated x to get sint + acost. Is that even right?
Then substituted cos^2 t with 1/2(cos2t + 1)

Then got y = 1/2a(cos 2t + 1)
Then differentiated that to get:
1/2(cos2t + 1 - 1/2asin 2t).

I stopped there because I doubt that's right.

 

[GreyKode]

I think it should be
x=asin(theta) , y=acos^2(theta)

 

[The Ruler]

Of course. My bad.

 

[GreyKode]

Then got y = 1/2a(cos 2t + 1)
Then differentiated that to get:
1/2(cos2t + 1 - 1/2asin 2t).

????
d/dt simply = -2(cos(t))(sin(t))