Author Topic: Maths 3A/3B (Read 54683 times) Tweet Share

conic curve · « **Reply #45 on:** September 15, 2016, 09:33:52 am »

Quote from: jamonwindeyer on September 15, 2016, 09:29:11 am

No no don't apologise, totally not necessary! Just know that we'll always get it done ASAP for you, but that won't always be within 24 hours, just keep it in mind for when you get feedback in the future because I'd hate to not be able to help you out

Jamon sorry to get off track but where are your prelim legal studies notes?

jamonwindeyer · « **Reply #46 on:** September 15, 2016, 09:39:34 am »

Quote from: conic curve on September 15, 2016, 09:33:52 am

Jamon sorry to get off track but where are your prelim legal studies notes?

Right Here

conic curve · « **Reply #47 on:** September 15, 2016, 09:41:03 am »

Quote from: jamonwindeyer on September 15, 2016, 09:39:34 am

Right Here

Oh right thanks

Does it cover every single dotpoint in the prelim syllabus?

jamonwindeyer · « **Reply #48 on:** September 15, 2016, 09:57:09 am »

Quote from: conic curve on September 15, 2016, 09:41:03 am

Oh right thanks

Does it cover every single dotpoint in the prelim syllabus?

From memory it covers most of them, but I might have missed stuff in the case studies towards the end? Best to compare with the syllabus to confirm

RuiAce · « **Reply #49 on:** September 15, 2016, 12:40:28 pm »

Quote from: anotherworld2b on September 14, 2016, 11:17:37 pm

The file was too large.question pic

$\text{You made a mistake where you said }\\ f(x+h)=2x(x+h)^2$
$\text{It should be }f(x+h)=2(x+h)(x+h)^2$
$\text{Because }f(x)=2x^3 \implies f(x+h)=2(x+h)^3$

anotherworld2b · « **Reply #50 on:** September 17, 2016, 01:34:22 am »

Hi im back with some more questions. I am having trouble understanding how to approach q7. I was a bit confused how to do the other question as well.

Thank you very much for your help ruiace and jamonwindeyer I really appreciate your help with answering my questions

I will ensure that if I have essay i
Would liked marked i will post it days before its due.

RuiAce · « **Reply #51 on:** September 17, 2016, 07:31:30 am »

Quote from: anotherworld2b on September 17, 2016, 01:34:22 am

Hi im back with some more questions. I am having trouble understanding how to approach q7. I was a bit confused how to do the other question as well.

Thank you very much for your help ruiace and jamonwindeyer I really appreciate your help with answering my questions
I will ensure that if I have essay i
Would liked marked i will post it days before its due.

$\text{John's conjecture is wrong as when }x=10\\ 10^3-10=990\text{ which is not divisible by }12.\\\text{i.e. All you need to prove that he is wrong is a counterexample.}$
$\text{Inspiration: Upon factorising}\\ \boxed{x^3-x=(x-1)x(x+1)}\\ \text{which is just the product of three consecutive integers.}$
$\text{When }x\text{ is odd, the expression is always divisible by 12}\\ \textit{You should try to figure out why.}$
$\text{On the other hand if }x\text{ is even, that might not be the case.}\\ \text{Try an even number that's not a multiple of }4\text{, i.e. }10$
$\textit{However, you can conjecture that it's divisible by something else...}$
Leaving this post unfinished for you to do some work yourself. Come back later if you tried and still couldn't finish

RuiAce · « **Reply #52 on:** September 17, 2016, 07:49:56 am »

Quote from: anotherworld2b on September 17, 2016, 01:34:22 am

Hi im back with some more questions. I am having trouble understanding how to approach q7. I was a bit confused how to do the other question as well.

Thank you very much for your help ruiace and jamonwindeyer I really appreciate your help with answering my questions
I will ensure that if I have essay i
Would liked marked i will post it days before its due.

$\begin{align*}y&=ax^3\implies \frac{dy}{dx}=3ax^2\end{align*}\\ \text{When }x=-1\text{ we have }\frac{dy}{dx}=3a$
$\frac{dy}{dx}\text{ gives the gradient of the tangent, but we know that it is PERPENDICULAR}\\ \text{to the line }y=2x+3\\ \text{The gradient of }y=2x+3\text{ is obviously }2$
$\text{So using the formula they give us:}\\ 3a \times 2 = -1\implies \boxed{a= -\frac{1}{6}}$
$\text{Then }y=-\frac{1}{6}x^3\\ \text{When }x=-1, \,y=b\\ \text{So }\boxed{b=\frac{1}{6}}$

anotherworld2b · « **Reply #53 on:** September 17, 2016, 01:11:55 pm »

Thank you for your help ruiace
I am a bit confused on how to do these questions as well

RuiAce · « **Reply #54 on:** September 17, 2016, 01:20:10 pm »

Quote from: anotherworld2b on September 17, 2016, 01:11:55 pm

Thank you for your help ruiace
I am a bit confused on how to do these questions as well

First question just asks you to subtract one y-value from the other.

For average rate of change, use the gradient formula rise/run.
$x=2 \implies y=16\\ x=5\implies y=250\\ \text{Gradient }=\frac{250-16}{5-2}$

Instantaneous just means compute the derivative and substitute in your value. Because that's what the derivative essentially is in physics.

jamonwindeyer · « **Reply #55 on:** September 17, 2016, 01:23:37 pm »

Quote from: anotherworld2b on September 17, 2016, 01:11:55 pm

Thank you for your help ruiace
I am a bit confused on how to do these questions as well

Hey!

a) Substitute x=2 and x=5 into the equation, tell me by how much y changes between the two!
b) Remember we define the average rate of change between two points as:

$\text{Rate of Change}=\frac{\bigtriangleup y}{\bigtriangleup x}$

c) and d) Are your derivatives, $\frac{dy}{dx}$ at each respective point. Remember that instantaneous change is what the derivative measures!

And your final question is simultaneous equations, and then once you have two solutions, finding the value of the derivative at each of those points. Hint: When you are solving the simultaneous, you will end up with this quadratic:

$8x^2-8x-16=0\\x^2-x-2=0$

Solving that will give you the two x-value components of your two solutions (substitute back into one of the others to get the y-coordinates, as usual)

Edit: Whoops, Rui posted too, oh well

RuiAce · « **Reply #56 on:** September 17, 2016, 01:27:37 pm »

Quote from: jamonwindeyer on September 17, 2016, 01:23:37 pm

Edit: Whoops, Rui posted too, oh well

Mate, use /Delta not /bigtriangleup

Edit:: Soz, hit modify not quote

jamonwindeyer · « **Reply #57 on:** September 17, 2016, 01:34:13 pm »

Quote from: RuiAce on September 17, 2016, 01:27:37 pm

Mate, use /Delta not /bigtriangleup

$\bigtriangleup\text{ vs }\Delta$

Hmm, this one isn't too bad, but in general I like the formatting of \bigtriangleup a little better! I remember writing an exam for a student with \Delta and having the triangles just reduce to nothing if I did anything tricky, so I got into a (probably bad) habit, because the triangle is bigger (ironically)

anotherworld2b · « **Reply #58 on:** September 18, 2016, 04:29:27 pm »

I have a methods test on 'patterns' but I'm not sure what topics would fit under this topic.
Our teacher simply told us its on 'patterns' so I'm not sure what to study.
Would series and sequences, combinatorics fit under 'patterns?'

jamonwindeyer · « **Reply #59 on:** September 18, 2016, 04:39:27 pm »

Quote from: anotherworld2b on September 18, 2016, 04:29:27 pm

I have a methods test on 'patterns' but I'm not sure what topics would fit under this topic.
Our teacher simply told us its on 'patterns' so I'm not sure what to study.
Would series and sequences, combinatorics fit under 'patterns?'

Loosely, I'd say yes, but only someone who is doing/has done the WACE would know for sure

you should consult your syllabus!

Be sure to clarify this sort of stuff with your teacher in the first instance too! Like, you deserve to know what topics to study for your test, aha

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Author Topic: Maths 3A/3B (Read 54683 times) Tweet Share

conic curve

Re: Maths 3A/3B

jamonwindeyer

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conic curve

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jamonwindeyer

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RuiAce

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anotherworld2b

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RuiAce

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RuiAce

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anotherworld2b

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RuiAce

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jamonwindeyer

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RuiAce

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jamonwindeyer

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anotherworld2b

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