VCE Methods Question Thread!

[alex1234]

Actually, your working just proves my answer correct because your equation for the discriminant is wrong. You've solved for a negative discriminant, so you've solved for the complement of the case that I proved. You're meant to take the area above that line which would yield 1/4.
But your explanation is easier to follow than mine.

Do you mean take the area under the graph instead?

[knightrider]

Just a question about the methods exam.

as GA1 refers to sacs

GA2 refers to exam 1

GA3 refers to exam 2

Say for example you get a C+ on GA2

and then you get a A+ on GA3

Do these scores ever change like get moderated.
Or what you get on the exam stays as your score?

Many thanks 

Can anyone give their opinion to this 

[lzxnl]

They're bell-curved. But that's it. Why would they be moderated?

[alex1234]

Can anyone give their opinion to this 

no your exam scores never change but your sacs are moderated based on your cohorts performance and your relative ranking

[Floatzel98]

A few questions:

Would I be penalized if I simplified an expression to cot(x) in a methods exam. I accidentally did this probably thinking it was a spesh exam and don't know whether it is allowed.

With related rates questions, cone problems specifically, I was given the radius and height in meters to find r in terms of h but then later on dV/dt was given in cm^3/s. Does the change of units in this case matter? I'm guessing not because you only worked out a similarity between radius and height and the similarity would be the same even if you used different units. Also I'm just wondering if there are ways to do questions (calculus in general) when you have multiple variables. We have always had to reduce expressions like volume down to single variables through similar triangles to use calculus to solve for things. Are there ways that make it possible to do this?

Thanks

[studentofthenow]

Can someone explain to me how to do 2014 vcaa Extended response question 25 using related rates?

[alex1234]

A few questions:

Would I be penalized if I simplified an expression to cot(x) in a methods exam. I accidentally did this probably thinking it was a spesh exam and don't know whether it is allowed.

With related rates questions, cone problems specifically, I was given the radius and height in meters to find r in terms of h but then later on dV/dt was given in cm^3/s. Does the change of units in this case matter? I'm guessing not because you only worked out a similarity between radius and height and the similarity would be the same even if you used different units. Also I'm just wondering if there are ways to do questions (calculus in general) when you have multiple variables. We have always had to reduce expressions like volume down to single variables through similar triangles to use calculus to solve for things. Are there ways that make it possible to do this?

Thanks

I don't remember using cot(x) in any methods question, and if so it would be totally allowed to simplify that into something that you are comfortable to work with, as long as they are valid of course.

For your other question, you will need to take into account that your calculations have both m and cm in it, you will have to change the cm into m or vice versa, while the units of the cone maybe the same that means that the similar triangles will hold, this does not imply that the volume with respect to time will also be in m^3. Therefore you will need to change the units.

For the last question, i don't think there is any other way of the top of my head, it is best not to tinker around and just learn the material.

[alex1234]

A few questions:

Would I be penalized if I simplified an expression to cot(x) in a methods exam. I accidentally did this probably thinking it was a spesh exam and don't know whether it is allowed.

With related rates questions, cone problems specifically, I was given the radius and height in meters to find r in terms of h but then later on dV/dt was given in cm^3/s. Does the change of units in this case matter? I'm guessing not because you only worked out a similarity between radius and height and the similarity would be the same even if you used different units. Also I'm just wondering if there are ways to do questions (calculus in general) when you have multiple variables. We have always had to reduce expressions like volume down to single variables through similar triangles to use calculus to solve for things. Are there ways that make it possible to do this?

Thanks

I don't remember using cot(x) in any methods question, and if so it would be totally allowed to simplify that into something that you are comfortable to work with, as long as they are valid of course.

For your other question, you will need to take into account that your calculations have both m and cm in it, you will have to change the cm into m or vice versa, while the units of the cone maybe the same that means that the similar triangles will hold, this does not imply that the volume with respect to time will also be in m^3. Therefore you will need to change the units.

For the last question, i don't think there is any other way of the top of my head, it is best not to tinker around and just learn the material.

[studentofthenow]

how do you do this question?

[keltingmeith]

how do you do this question?

We NEED the rest of the question...

[Alter]

We NEED the rest of the question...

2014 Exam 2 - ctrl+f jones http://www.vcaa.vic.edu.au/Documents/exams/mathematics/2014/2014mmcas2-w.pdf

[studentofthenow]

2014 Exam 2 - ctrl+f jones http://www.vcaa.vic.edu.au/Documents/exams/mathematics/2014/2014mmcas2-w.pdf

bump

[alex1234]

how do you do this question?

good old tasmania Jones.. hopefully we can see he/she again this year

[GeniDoi]

bump

Flip the dh/dt expression to be dt/dh, then set up a definite integral from the initial height (solving pi*h^3 = 216 for h) to the final height 1m and you obtain the amount of time it takes (21 years). From there just add it to 2010 and you get 2031.

[Alter]

Hi, I'm having trouble solving question 1c on the Insight 2015 paper 1.

"The average value of the function f:(-(3/2), infinity) ->R, f(x)=1/(3+2x) over the interval [1, k] is (ln(3)/10). Find the value of k.

The solutions give the answer 6, but they don't really show the algebra. They just leave it at "setting __ = to ln(3)/10 yields k=6". I understand how to do these types of problems, but the algebra that I'm doing gives really ridiculous, impossible to solve by hand stuff. E.g. I got up to (k-1)*(ln(3)) = 10 (ln((2k+3)^(1/2)/5^(1/2))) in the working, which is clearly not doable. Any help?