Hutchoo's spesh thread.

[Hutchoo]

Yeah, the mistake was with simplifying the integral.
Cause
(2+6x) * 1/ sqrt(4-x^2) = (2+6x)/ sqrt(4-x^2)
That was my logic, anyway.

So then I just did:
int (2x+6) dx * int (1/sqrt(4-x^2)) dx. Which didn't work.

[Hutchoo]

Question 1 E : VCAA 2006 (SA)
http://www.vcaa.vic.edu.au/Documents/exams/mathematics/2006specmaths2-w.pdf
How did they know that A = ?
I understand that's the area for a circle, but why do they assume a wine glass is a circle 0-o?


Also: wtf?

Question 3iii.
I found the correct time (31. second, so I continued to use straight line motion, which is what they do as well (they = VCAA).

I used s = ut + 1/2at^2, they used v^2 = u^2 + 2as.
How come they give  different values?!


How did they get the graph for 4d? :/

[Bhootnike]

Question 1 E : VCAA 2006 (SA)
http://www.vcaa.vic.edu.au/Documents/exams/mathematics/2006specmaths2-w.pdf
How did they know that A = ?
I understand that's the area for a circle, but why do they assume a wine glass is a circle 0-o?

thats what i said..!
bullshit innit!

Question 3iii.
I found the correct time (31. second, so I continued to use straight line motion, which is what they do as well (they = VCAA).

I used s = ut + 1/2at^2, they used v^2 = u^2 + 2as.
How come they give  different values?!

they dont :p
i used the same forumula as you.
what values did you use?
i had t = 31.82...., a = 2.2, v = 70, u = 0
so x just = 0.5a^2
= 0.5 x 2.2 x 31.82^2
= 1113.636
=1114 m

[Hutchoo]

Ahhhhhh, my bad I meant iTute!

Wtf, I'm an idiot! I did a calculator error:
I typed t to be 31.8, not 31.82, which accounts for 1112 and not 1114
@ that stupid circle thing:
:/ I know lol. That thing really confused me. Worth 3 marks, I was stumped tbh. It was a very easy question though, that's the worst part.


Also:
Question 5b. I don't really understand this question. Anyone care to explain? =)*looking at you bhootnike*

[Bhootnike]

Ahhhhhh, my bad I meant iTute!

Wtf, I'm an idiot! I did a calculator error:
I typed t to be 31.8, not 31.82, which accounts for 1112 and not 1114
@ that stupid circle thing:
:/ I know lol. That thing really confused me. Worth 3 marks, I was stumped tbh. It was a very easy question though, that's the worst part.


Also:
Question 5b. I don't really understand this question. Anyone care to explain? =)*looking at you bhootnike*

lol its ok! i dot that!
and yea i know right, i still dont agree with that ..!

cos pi /8?
use double angle formula. cos 2 x pi/8 = cos pi/4 remember :p

[Hutchoo]

Oh, my bad, I meant a ii. xD

[Bhootnike]

Oh, my bad, I meant a ii. xD

aii)
i didnt get it either lOL.

[Hutchoo]

Oh, my bad, I meant a ii. xD

aii)
i didnt get it either lOL.

/ping b^3!

[pi]

Oh, my bad, I meant a ii. xD

aii)
i didnt get it either lOL.

/ping b^3!

I'm taking over this shit

Basically, for sake of me ceebsing latex, let z-line-on-the-top (complement) = y

Ok, so basically the question is asking for the line between points z and -z in terms of y.

So the equation is |z-y|=|-z-y|, which (and remember back to loci!) means that the distance between z and y is equivalent to the distance between -z and y.

(N.B. the equation can be further simplified to |z-y|=|z+y|)

Does that make sense? :/


edit: forgot a word in the sentence -_-

[Hutchoo]

OHHHHHHHHHHHHHHHHHH YEAH.
The distance thing!

Derrick Ha said the exact same thing in his lectures, can't believe I forgot that.
SO if you say that two points are equal distance, you're essentially showing that they form a line?

I need to understand this before I explode!

[pi]

Yep

[Hutchoo]

Yep

Thank you <3


Can someone explain this though?

Yeah, the mistake was with simplifying the integral.
Cause
(2+6x) * 1/ sqrt(4-x^2) = (2+6x)/ sqrt(4-x^2)
That was my logic, anyway.

So then I just did:
int (2x+6) dx * int (1/sqrt(4-x^2)) dx. Which didn't work.

[pi]

So then I just did:
int (2x+6) dx * int (1/sqrt(4-x^2)) dx. Which didn't work.

Unsure on the context, but this is not a legitimate step.

For example, integrate x^2, answer is x^3/3. But if you did int(x)*int(x) you'd get (x^2/2)*(x^2/2)=x^4/4, which is incorrect. You can only split the integral for + or - .

[Hutchoo]

Context: Go to page one.
And yeah, I understand that. But with fractions, you can simplify the numerator/denominator by taking it out of the integral.

I.e: int (2/x) = 2*int(1/x) = 2 loge (x)

That's why I don't understand why my method didn't work :/

[pi]

Context: Go to page one.
And yeah, I understand that. But with fractions, you can simplify the numerator/denominator by taking it out of the integral.

I.e: int (2/x) = 2*int(1/x) = 2 loge (x)

That's why I don't understand why my method didn't work :/

Because removing a constant is different to removing (2x+6)


(I feel I'm still missing your point though :/ )