# Carrotsticks' Solutions 2015 Extension 2 HSC (1 Viewer)

#### lpodtouch

##### Active Member
Thanks for taking the time to write up these solutions. What do you think the E4 cut off will be for this year's exam out of curiosity?

#### HardlyProductive

##### New Member
Thanks Carrot. Thoughts on the paper?

#### jackleung34

##### Member
omfg i integrated one side of the square too lol i thought i was the only one in the state who could be so stupid
omg i did too shit man

#### Mathsisfun15

##### Active Member
Now my careless errors will haunt me forever. How I screwed up the product rule I will never know

##### Member
hey carrot how many marks would i lose for saying the product of the coses in the second last question was (-1)^n

#### Drsoccerball

##### Well-Known Member
hey carrot how many marks would i lose for saying the product of the coses in the second last question was (-1)^n
1

#### Drsoccerball

##### Well-Known Member
Carrot what do program do you use to type up your exams and solutions?

#### Mathsisfun15

##### Active Member
hey carrot how many marks would i lose for saying the product of the coses in the second last question was (-1)^n
Damn I did that too

#### Carrotsticks

##### Retired
hey carrot how many marks would i lose for saying the product of the coses in the second last question was (-1)^n
If that is all you just said, with nothing else, then most likely zero.

The mark allocation I am guessing for that Q is

1 for finding the roots

1 for using product of roots and acquiring the correct answer (not necessarily closed form)

1 for finding the closed form for the binomial series

That last mark may or may not be there, it could perhaps be allocated towards simply identifying that the product of roots was relevant to the question.

Now my careless errors will haunt me forever. How I screwed up the product rule I will never know
If it makes you feel better, I stuffed that one up too when doing the solutions. Only realised it was wrong when my result was useless for the next part.

Carrot what do program do you use to type up your exams and solutions?
Math Type and Microsoft Word. Diagrams also done using Microsoft Word.

##### Member
If that is all you just said, with nothing else, then most likely zero.

The mark allocation I am guessing for that Q is

1 for finding the roots

1 for using product of roots and acquiring the correct answer (not necessarily closed form)

1 for finding the closed form for the binomial
that wasnt all i said - i worked out the roots and wrote the formula for product of roots but i used the leading coefficient as one instead of the sum of binomial coefficients

#### JACO

##### New Member
That's exactly what I did, then used trial and error to try and see if I was right, but then when I subbed n = 1, the product came to -1/2, then tried with n = 2, and the product came to 1/8, then when n = 4, the product was =-1/32 ... so I knew the denominator was increasing by odd powers of 2, which is 2^(2n-1), so I just put (-1)^n / 2^(2n-1) as my final answer, without evaluating the sum of the binomials. Hopefully 2/3 marks.

#### 4025808

##### Well-Known Member
Holy shit the probability was fucked, gg for that one. Did not see that one coming. But apart from that the rest of the paper didn't seem too difficult tbh.

#### RealiseNothing

##### what is that?It is Cowpea
that wasnt all i said - i worked out the roots and wrote the formula for product of roots but i used the leading coefficient as one instead of the sum of binomial coefficients
Probably only 1/3 if you got (-1)^n but you never know.

Thank you all !

#### sida1049

##### Well-Known Member
Holy shit the probability was fucked, gg for that one. Did not see that one coming. But apart from that the rest of the paper didn't seem too difficult tbh.
Yep - that pretty much sums up my experience of the exam.