# BoS trials Maths and Chemistry 2020 (2 Viewers)

#### OnJob

##### New Member
It's like 12 posts up....
Yeah sorry I couldn't find it because my site wouldn't show the "newer" posts. Thanks though!

#### turtle67

##### Member
Just some hints:

E is a tertiary alcohol (2-methylbutan-2-ol) as it is not oxidising by the oxidising agent

C is 2-bromo-2-methylbutane as it makes E through a substitution

A is an alkene. It is 2-methylbut-1-ene. It must be the but-1-ene bit because it needs to make a primary alcohol to make the carboxylic acid in compound F

B is 1-bromo-2-methylbutane. Other isomer of the addition reaction of HBr

D is 2-methylbutan-1-ol

F is a carboxylic acid

G is a sodium salt

H and I are made because it can react two ways either alcohol + carboxylic acid = ester

or amine + carboxylic acid = amine
this year 12 chemistry looks like a bit of a step up from year 11 lol

#### BlueGirl18

##### New Member
Hi! Just wondering if the solutions will be uploaded soon? Many thanks!!

#### MrGresh

##### Member
this year 12 chemistry looks like a bit of a step up from year 11 lol
Haha yep. The stuff in that question is organic chemistry, which looks a lot more confusing than it is!

Year 12 chem is pretty complex but also super rewarding, so enjoy it!

#### turtle67

##### Member
Haha yep. The stuff in that question is organic chemistry, which looks a lot more confusing than it is!

Year 12 chem is pretty complex but also super rewarding, so enjoy it!
I'll try my best to enjoy it ahah, good luck in your exams

#### pikachu975

##### I love trials
Moderator
this year 12 chemistry looks like a bit of a step up from year 11 lol
Yeah haha also keep in mind the BOS trials are usually harder than the HSC if you want to challenge yourself! They're worth a try to improve problem solving skills and to see where you're at ^^

#### Trebla

##### Administrator
Administrator
We should be in a position to release solutions and results for Maths Ext2 in the next 2-3 days. In the meantime, if there are any specific questions you want an outlined solution for, just ask and I can reply.

2xq

#### Trebla

##### Administrator
Administrator
Since multiple people keep asking, the Chemistry paper is located on page 2 of this thread

#### YonOra

##### Member
Hi.

Are you able to provide me with the answers to Q13 b) i) for the Maths Ext 1 BoS 2020 Trials paper please? Thank you!

P.S. hats off to you for this Q. I have never been stumped by an Induction question. Really, really made me think.

#### Trebla

##### Administrator
Administrator
Hi.

Are you able to provide me with the answers to Q13 b) i) for the Maths Ext 1 BoS 2020 Trials paper please? Thank you!

P.S. hats off to you for this Q. I have never been stumped by an Induction question. Really, really made me think.
Will just outline it here, because it is quite long to type in full.

You need to prove

$\bg_white \alpha^{k+1}(p-\beta q) = x_{k+2}-\beta x_{k+1}$

Use the definition of $\bg_white x_{k+2}$

$\bg_white x_{k+2}-\beta x_{k+1} = x_{k+1}(a-\beta)+bx_k$

But

$\bg_white \alpha\beta = -b$

and

$\bg_white \alpha+\beta=a$

Hence

$\bg_white x_{k+1}(a-\beta)+bx_k = \alpha (x_{k+1}-\beta x_k)$

You can then apply the assumption to get the final answer.

#### YonOra

##### Member
Will just outline it here, because it is quite long to type in full.

You need to prove

$\bg_white \alpha^{k+1}(p-\beta q) = x_{k+2}-\beta x_{k+1}$

Use the definition of $\bg_white x_{k+2}$

$\bg_white x_{k+2}-\beta x_{k+1} = x_{k+1}(a-\beta)+bx_k$

But

$\bg_white \alpha\beta = -b$

and

$\bg_white \alpha+\beta=a$

Hence

$\bg_white x_{k+1}(a-\beta)+bx_k = \alpha (x_{k+1}-\beta x_k)$

You can then apply the assumption to get the final answer.
How did you get the definition of (
$image=https://latex.codecogs.com/png.latex?\bg_white%20x_{k+2}-\beta%20x_{k+1}%20=%20x_{k+1}(a-\beta)+bx_k&hash=2c4e190b9434f9b8568416cdad767363$

#### YonOra

##### Member
How did you get the definition of (
$image=https://latex.codecogs.com/png.latex?\bg_white%20x_{k+2}-\beta%20x_{k+1}%20=%20x_{k+1}(a-\beta)+bx_k&hash=2c4e190b9434f9b8568416cdad767363$
And (from what i can see from that definition) you can't use the roots and coefficient rules?

#### ikindawannasleep

##### New Member
Pending someone giving that, feel free to name a handful of specific questions you want to know the answer to and we can provide a brief outline of the solution.
hiii roughly when will the chem answers be uploaded?

#### Trebla

##### Administrator
Administrator
How did you get the definition of (
$image=https://latex.codecogs.com/png.latex?\bg_white%20x_{k+2}-\beta%20x_{k+1}%20=%20x_{k+1}(a-\beta)+bx_k&hash=2c4e190b9434f9b8568416cdad767363$
Use this on the RHS of what you are trying to prove
$\bg_white x_n=ax_{n-1}+bx_{n-2}$
And (from what i can see from that definition) you can't use the roots and coefficient rules?
Note that $\bg_white \alpha$ and $\bg_white \beta$ are the roots of the equation $\bg_white x^2=ax+b$

#### Trebla

##### Administrator
Administrator
hiii roughly when will the chem answers be uploaded?
Sorry, there is a bit of a backlog in getting Maths out before Chemistry as the Maths HSC exams start on Monday and the Chemistry HSC is still a while away. If you have any specific questions you want to know the answer to, just post it here.

#### KingSabi6

##### New Member
Sorry, there is a bit of a backlog in getting Maths out before Chemistry as the Maths HSC exams start on Monday and the Chemistry HSC is still a while away. If you have any specific questions you want to know the answer to, just post it here.
when will the math solutions be uploaded considering the exams are in a few days?

#### Trebla

##### Administrator
Administrator
when will the math solutions be uploaded considering the exams are in a few days?
Maths Ext2 results and solutions will be released tonight...

#### Trebla

##### Administrator
Administrator

Here are the solutions and student results for the 2020 Mathematics Extension 2 BoS trials. Thanks to everyone who participated and for your patience!

A reminder that whilst the questions are made to be as closely styled to the HSC exams as possible, this is NOT intended to be an accurate reflection of the difficulty of the HSC exam. So don't get too hung up on the mark you got. It is designed to give you good practice in exercising your problem solving skills in preparation for those harder questions in the exam.

Please note that the question paper has also been updated (in the same post I originally posted it) to include further minor edits to wordings and typos. If you find any typos in the solutions, please flag that for our consideration.

Best of luck for the HSC exam on Monday!

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#### Drdusk

##### π
Moderator
Aye good job to the person who got 72! Well done to everyone else as well.

Seems question 16 destroyed everyone this year.

#### 2xq

##### New Member
Aye good job to the person who got 72! Well done to everyone else as well.

Seems question 16 destroyed everyone this year.
seemed like the marker had a great time marking q16!!! ;D