VCE Methods Question Thread!

[cosine]

The largest domain that cos u is one to one is something like [0, pi]. You therefore want log_a(x) to only take these values. Try the rest yourself now,

Haha I don't get anything of what you said

Need help with the attached, please.

Also, If y = 2tan(2x), then dy/dx ? Answer says 2sec^2(2x) from the 2003 exam 1 VCAA, anyone keen to explain to me why?

Many thanks

[Adiamond]

May someone show me how to logically tackle this question, without the abuse of the assessors report, in other words, can someone show me why and how they get the answer? Please?

Wow lzxnl's way is MUCH much easier than mine (use that),
I actually did this question yesterday when i was doing that darned exam and i legitimately plugged in the values into my calculator, i used a = 10 because that is the normal log that you see a lot and graphed cos(log₁₀(x)) with the different range restrictions using the calculators domain button ( | ) if i recall correctly and saw the values for which h(x) was a one-to-one function. (seriously though this was a very tedious method and i don't recommend it in the slightest, but if you're stuck like i was just plug values in).

[cosine]

Wow lzxnl's way is MUCH much easier than mine (use that),
I actually did this question yesterday when i was doing that darned exam and i legitimately plugged in the values into my calculator, i used a = 10 because that is the normal log that you see a lot and graphed cos(log₁₀(x)) with the different range restrictions using the calculators domain button ( | ) if i recall correctly and saw the values for which h(x) was a one-to-one function. (seriously though this was a very tedious method and i don't recommend it in the slightest, but if you're stuck like i was just plug values in).

It might be easier, but yours actually makes sense. Cheers xD

[TheAspiringDoc]

Haha I don't get anything of what you said

Need help with the attached, please.

Also, If y = 2tan(2x), then dy/dx ? Answer says 2sec^2(2x) from the 2003 exam 1 VCAA, anyone keen to explain to me why?

Many thanks

In image three, what does the pronumeral 'c' represent?

[cosine]

In image three, what does the pronumeral 'c' represent?

Combination, nCr() on CAS. It's a binomial distribution formula

[odeaa]

I just tried to solve a question (quite complicated) on my ti-nspire (up to date software), and it says "resource overload" and refuses to give me an answer

In the worked solutions (insight 2013) they are using the classpad and they do the exact same thing but it works fine for them

Is this just a shit question that they would never give you on the vcaa exam? Why has my cas let me down in a time of such need?

[StupidProdigy]

I just tried to solve a question (quite complicated) on my ti-nspire (up to date software), and it says "resource overload" and refuses to give me an answer

In the worked solutions (insight 2013) they are using the classpad and they do the exact same thing but it works fine for them

Is this just a shit question that they would never give you on the vcaa exam? Why has my cas let me down in a time of such need?

I think they'd be more likely to give it on an exam because it'd show the abilities of some students to get around the problem. I've had situations like this a few times. Try anything that comes to mind which might help the cas (changing answers to approximate instead of exact for example). Don't suppose you could put the question up or pm me so I could try with cas?

[cosine]

Haha I don't get anything of what you said

Need help with the attached, please.

Also, If y = 2tan(2x), then dy/dx ? Answer says 2sec^2(2x) from the 2003 exam 1 VCAA, anyone keen to explain to me why?

Many thanks

Anyone?

[odeaa]

Anyone?

I have no idea, cas says 4sec^2(x) and thats what i get by hand. Are you sure you have the question right?

[StupidProdigy]

Just putting it out there, the examiners are humans and may make this thing called a typo

[cosine]

I have no idea, cas says 4sec^2(x) and thats what i get by hand. Are you sure you have the question right?

It's right xD

Anyone?

Anyone?

[Zealous]

Haha I don't get anything of what you said

Need help with the attached, please.

Also, If y = 2tan(2x), then dy/dx ? Answer says 2sec^2(2x) from the 2003 exam 1 VCAA, anyone keen to explain to me why?

Many thanks

I'm pretty busy so here's some really brief explanations (but may be wrong).

Q17:
It's crazy integral notation by looking at adding up infinitismally small chunks. Basically, they're just substituting different values into xi, infinite times (as delta x approaches zero) to find the area under the curve y=x and this is actually the same as integrating 'x' from 0 to 4. So the answer should be E, 8.

Normal Distribution:
Both the means are the same since the middle points are the same. So it can either be C or D. Now we need to find which one has the greater spread around the mean, which means things deviate more (bigger standard deviation). Standard deviation 2 is larger, so the answer is D!

Bread Rolls:
Find the probability of not getting a multigrain at all - so that means the probability of getting a white, then another white bread. Then do 1 minus that probability to the find probability that we get at least a multigrain.

VCAA 2003:
Should probably be 4sec^2(2x).

[cosine]

Thanks Zealous, very helpful again.

With the attached question, we are require to draw the derivaive function for the red and blue regions of the f(x). The black lines are the answer, however, for the modulus part of the graph, my two black lines were the same but not spaced so close to the x-axis, more further away from it but I still had the right endpoints etc.. Would mark be given on an exam? If not, how are we meant to know that the two lines are close to the x-axis? I understand the lines have the same mgnitude, because their rate of change is the same but with different signs, thank you.

[keltingmeith]

Thanks Zealous, very helpful again.

With the attached question, we are require to draw the derivaive function for the red and blue regions of the f(x). The black lines are the answer, however, for the modulus part of the graph, my two black lines were the same but not spaced so close to the x-axis, more further away from it but I still had the right endpoints etc.. Would mark be given on an exam? If not, how are we meant to know that the two lines are close to the x-axis? I understand the lines have the same mgnitude, because their rate of change is the same but with different signs, thank you.

Because this is so approximate, exact position doesn't matter - but, relative does.

As long as they were before the parabola's gradient and same magnitude/shape, you should be fine and get the marks.

[cosine]

Because this is so approximate, exact position doesn't matter - but, relative does.

As long as they were before the parabola's gradient and same magnitude/shape, you should be fine and get the marks.

what do you mean