Official BOS Trial 2015 Thread (5 Viewers)

Paradoxica · Oct 2, 2015

you bolted early

leehuan · Oct 2, 2015

I only attempted 43 marks lol so ashamed...

The volumes question threw me off big time. I forgot how to do volumes after that.

DatAtarLyfe · Oct 2, 2015

shiiit, the big guns in maths getting demolished by carrot
what is this sorcery?

lita1000 · Oct 2, 2015

Were there any big names at the exam? Apparently there were a few olympians last year.....

Ekman · Oct 2, 2015

Never knew pyramids had curved edges...

Drsoccerball · Oct 2, 2015

Paradoxica said:
you bolted early

Tbh i didnt even have to go i was just so sick of it i left... I think if i did ex 1 and 2 on different days the results qould of been better...

kawaiipotato · Oct 2, 2015

The volumes was interesting did anyone get it out? Did we have to prove that the area was in a ratio? Bc. I just assumed it and it worked

Drsoccerball · Oct 2, 2015

Gabriel's like "Im Gabriel Moussa" everyone's like"whos that..." really -.-?

DatAtarLyfe · Oct 2, 2015

didnt you guys get solutions on your way out?

Drsoccerball · Oct 2, 2015

DatAtarLyfe said:
didnt you guys get solutions on your way out?

No I didn't pick up Ekman's paper on my way out.

leehuan · Oct 2, 2015

How were we meant to do the first integral on Q11?

Ekman · Oct 2, 2015

leehuan said:
How were we meant to do the first integral on Q11?

for 4u or 3u?

leehuan · Oct 2, 2015

4 (I didn't do 3U)

Drsoccerball · Oct 2, 2015

leehuan said:
How were we meant to do the first integral on Q11?

u^2 =sinx

Ekman · Oct 2, 2015

leehuan said:
4 (I didn't do 3U)

$I = \int \frac{\sqrt{\sin{x}}}{\cos{x}\sin{x}} dx $ Let $ u^2 = \sin{x}$

$\therefore I = \int \frac{2u^2}{\cos^{2}{x} u^2} du = \int \frac{2u^2}{(1-u^4) u^2} du$

$I = \int \frac{2du}{1-u^4} du = \int \frac{1}{1-u^2} + \frac{1}{1+u^2} du = \frac{1}{2}\int \frac{1}{1-u} + \frac{1}{1+u} du + \int \frac{1}{1+u^2} du$

$= \frac{1}{2} \ln\left(\frac{1+\sqrt{\sin{x}}}{1-\sqrt{\sin{x}}} \right) + \tan^{-1}{(\sqrt{\sin{x}})} + c$

leehuan · Oct 2, 2015

Oh wow. All of my efforts actually didn't go to waste!

Except, i went a longer route and did u=sin(x) because I didn't see that u^2=sin(x) would work [Tried at the start when my brain wasn't working]

Drsoccerball · Oct 2, 2015

For 11C i got p=0 as my only values what did everyone else get?

Paradoxica · Oct 2, 2015

leehuan said:
Oh wow. All of my efforts actually didn't go to waste!

Except, i went a longer route and did u=sin(x) because I didn't see that u^2=sin(x) would work [Tried at the start when my brain wasn't working]

Whenever you see an nth root of a basic trigonometric function, your instinctive response should be $u^n = k* T(x)$ . Doesn't always work, but that's what I normally do. Sometimes, you'll need to do a bit of algebraic manipulation before making a substitution, but apart from that, it shouldn't require too much effort on your part.

deboiz · Oct 2, 2015

lita1000 said:
Were there any big names at the exam? Apparently there were a few olympians last year.....

There were two NMSS (math summer school so sorta olympiad training squad?) ppl there (that i knew of)

Paradoxica · Oct 2, 2015

Drsoccerball said:
For 11C i got p=0 as my only values what did everyone else get?

Ah. Yes, you see, the values were $\pm 2$ , I made the mistake of reading the $x^2$ term as $x$

Official BOS Trial 2015 Thread (5 Viewers)

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