VCE Methods Question Thread!

[Lear]

Does anyone have a list of fundamental math concepts that are often required to solve the tricky geometric questions in methods?
I'm talking about concepts like similar triangles, Pythagoras, basic circle theorems and scale factoring that are not taught in the Methods course but are necessary to solving some of the harder questions.

[TheBamboozler]

Fellas, probably simple but please help me out.

The population of a country is found to be growing continuously at an annual rate of 2.96% after 1 January 1950. The population t years after 1 January 1950 is given by the formula p(t) = (150×106)e^kt

Find the value of k.

[Lear]

f(x)= ax^3 + x^2 + bx + p
Where a,b,p are all real numbers except 0.

If f(x) has an inverse function,
Express b in terms of a.

[RuiAce]

f(x)= ax^3 + x^2 + bx + p
Where a,b,p are all real numbers except 0.

If f(x) has an inverse function,
Express b in terms of a.

i.e. it must have no stationary points, or just one single horizontal point of inflexion.

[Lear]

Shouldn’t we make the discrimination = 0 as a perfect cube has an inflection point where the gradient is 0?

[RuiAce]

Nobody said it had to be a perfect cube.

All you said was that it had to be invertible. Perfect cubes are just a special case of that.

[Lear]

Ah very true, my mistake.
Thank you!

[michaeljacksonftw]

Had my methods sac few days ago (entire unit 3) and didn't go too well. Still aiming for 35 raw, and considering that I have 2 months between my last methods sac in unit 4 and the exams, I am aiming for exam scores for 30/40 exam 1 and 60/80 exam 2. My question is how well of an understanding would I need to get these exam scores? How many practise exams should I do. I'm average at methods for my ability.
Thanks

[michaeljacksonftw]

Had my methods sac few days ago (entire unit 3) and didn't go too well. Still aiming for 35 raw, and considering that I have 2 months between my last methods sac in unit 4 and the exams, I am aiming for exam scores for 30/40 exam 1 and 60/80 exam 2. My question is how well of an understanding would I need to get these exam scores? How many practise exams should I do. I'm average at methods for my ability.
Thanks

Bump How can I improve my sac scores.? I'm putting in a lot of effort but still not getting ideal results

[S200]

Had my methods sac few days ago (entire unit 3) and didn't go too well. Still aiming for 35 raw, and considering that I have 2 months between my last methods sac in unit 4 and the exams, I am aiming for exam scores for 30/40 exam 1 and 60/80 exam 2. My question is how well of an understanding would I need to get these exam scores? How many practise exams should I do. I'm average at methods for my ability.
Thanks

Do as many practice exams as you can find that relate to the current study design.

I have my SAC in two or three weeks, thank goodness.. I am also aiming for a 35..

But yeah, again. I had a seminar thingy with Derick Ha the other day (in case you don't know him, he went nuts in everything he did.. except 48 in english...) and he said that doing the SAC is only half of it. By the repetition of the SAC's you learn where your most common errors are. If you make a "error Book", you can add a list of your most common errors to your summary book, which would be very useful when you are checking back through your exam in the last few minutes of examination time.

Hope this helps... Underlying message - as many as possible.

Bump How can I improve my sac scores.? I'm putting in a lot of effort but still not getting ideal results

I guess just by knowing the topic in depth...
and by getting a good nights rest the night b4...
and eating Tim Tams. Everything is better with Tim Tams...

[michaeljacksonftw]

y = x cos(x)
to find dy/dx using the product rule, how do we know which one is "u" and which one is "v" since there's both "x" and "cos(x)" so how do we know weather "x" is "u" or "v" and weather cos(x) is "u" or "v"
Thanks

[Sine]

y = x cos(x)
to find dy/dx using the product rule, how do we know which one is "u" and which one is "v" since there's both "x" and "cos(x)" so how do we know weather "x" is "u" or "v" and weather cos(x) is "u" or "v"
Thanks

Have a go trying it out both ways.
It won't matter and you will get the same answer either way

[michaeljacksonftw]

Have a go trying it out both ways.
It won't matter and you will get the same answer either way

But won't vcaa expect us to do it a certain way, and show working out?

[Sine]

But won't vcaa expect us to do it a certain way, and show working out?

nope vcaa won't care which way you do and technically don't even need to write out the "formula"
you can go
y = xcos(x)
y = (1)(cos(x))+ (x)(-sin(x))
....
By using the brackets you are impliciting showing your use of the formula.

[darkz]

y = x cos(x)
to find dy/dx using the product rule, how do we know which one is "u" and which one is "v" since there's both "x" and "cos(x)" so how do we know weather "x" is "u" or "v" and weather cos(x) is "u" or "v"
Thanks

Even thought the order you do it in doesn't matter for the product rule, it does actually matter for the quotient rule - so when you're taking the derivative of something like f(x) = [f(v)] / [f(u)]. In my opinion, the best way to memorise how it works isn't to simply remember the formula, but actually more of the idea behind it, etc. So like for the product rule, despite the order not mattering, always try to do it in one order, preferably the order for the quotient rule, so you won't mix it up or forget. For your example, x * cos(x), separate it into two parts, the x and the cos(x).
Then think of it as (derivative of 1st part) * (2nd part) + (1st part) * (derivative of 2nd part)
Then using (x) / cos(x) as an example of the quotient rule, think of it as [(derivative of 1st part) * (2nd part) - (1st part) * (derivative of 2nd part)] / (2nd part)^2

By doing it this way, you're less likely to get them mixed up / forget how to do it (There's no real need to know which one is 'u' or 'v')