Methods Question thread

DumbNerd

Should I actually do Methods 3/4 right now?

So my school decided (for the first time in like 10 years) to make an accelerated Methods class. Basically, we do Unit 3/4 in Year 11 so in y12 we have no more Methods. We've already gone through Units 1 and 2 this year (mind you I'm in Yr10). All out exams were based on Unit 1 and we just did one for Unit 2. The mark for that was using the 15-point system and I got 15/15 (94% tho lol 🤣 ).

The issue is we just started unit 3 and it's literally hell; there's just so much content to do in such little time (literally like 1 topic PER DAY) but I remind myself of the advantage I'll have in yr12. So, should I just go through it and torture myself this + next year? If you have any tips to study 5 pages of textbook content in one day, pls reply. My teacher wants all of us to get 90+ in our final ATAR result.

God

DumbNerd kk

QCE?

I did in in vic and went alright. So is doable. Idk about interstate though.

jinx_58

DumbNerd
That sounds terrible and somewhat alright at the same time. And damn! Units 1 n 2 in year 10??? That's crazy.

I suggest looking over the textbook summaries and belting out a few practice questions each night. If you know you can manage it in the next two years, go for it. Just be careful to not burn out.

-jinx_58

krodda

How do you do simultaneous solutions with four exponential equations?
I'm currently doing my year 11 Methods IA1, and I need to find an exponential model for a set of data points with the equation y=ae^b(x-c)+d. Using four data points, I need to sub them in to get four equations then solve simultaneously for the parameters. I was okay doing them with the cubic equation, but when it came to exponentials, I was completely lost. My teacher held tutorials, but wouldn't explain it to us one bit, kinda frustrating, and no one I know, not even my older sibling know how to approach it. Please send help

PhytoPlankton

krodda
Hey krodda,

Since it is your IA1 PSMT, you certainly could use your graphics calculator (technology) to solve the equations, write the answer down and state that you used technology to solve it. This can sometimes even be advantageous because one of the PSMT criteria is to use technology in your assignment. However, if you like to do it algebraically, then it would be great if you could post a picture of the four equations for me to see if it's possible (especially for a year 11).

Alternatively, you can enter those equations into SymbolLab or Wolfram Alpha and they will show you step-by-step solutions on how to solve almost any maths problem.

Hope that helps!

krodda

PhytoPlankton

Thanks so much! I do unfortunately have to show algebraic working, but I don't know how to post a picture, it wont let me, so I will try and type it out! If this helps, my teacher said that we can assume the parameter d as -1, for it to pass through the origin to make it easier, but we will get marked down, and I'm not sure I am willing to risk that many marks.

[1] 32=ae^(b(140-c))+d
[2] 64=ae^(b(190-c))+d
[3] 113=ae^(b(240-c))+d
[4] 180=ae^(b(290-c))+d

PhytoPlankton

krodda

That's all good. So I tried the problem and it became quite messy but with the help of my calculator, I managed to get somewhere. But I ended up with an equation that equals two random numbers which suggests it doesn't have a solution. Obviously, I thought I got it wrong somewhere so I went to the Symbolab website and entered all your equations in and surprisingly, I was right. They ended up with a value for d which made an equation that equals two random numbers and Symbolab concluded that there were no solutions to the question. If you would like to see it for yourself, this is the link to the Symbolab solution.

Maybe your equations could be wrong or your equations simply don't have a solution. I guess you could use the values they give for a, b, c and d and write that into your PSMT but you need to state that the equations don't have a solution.

Anyway, hope that helps and feel free to ask any more questions about this; it is quite confusing.

krodda

PhytoPlankton

Thank you so much for trying😭 I have checked with my teacher and my equations are correct, so I am so confused on what is going wrong. There has been so much controversy about our assessment this term as even some of my classmates' tutors can't help them solve it.

I think maybe they are reviewing the assessment to see if it is actually possible, but for now I am just going to try and solve it by assuming some of the parameters, partial marks is better than none I guess. Once again thanks so much for taking your time to help me, I'll see how this goes (it's due next wednesday).

Leepie

Hi there, anyone have QCE practice test for year 10?

Bibliii

I have a methods exam on the 24th of March and literally have no idea on where or what to start revising. Previously I've done really bad on my methods exam, even though I out a lot of effort, which is really demotivating. But since it's yr 12 I want it to count. Our exam is just integration and derivatives (it seems), and I wasn't really good with that content. I wanna be able to do some complex familiar questions as well but can't find any. Anyway long-story short, I'd just like some advice on what to do to prepare effectively and do well on the methods exam! Thank you everyone and enjoy your week, it's getting to a crazy time in term so hope you're all doing well!

Note: unfortunately I can't buy any study materials or anything because I haven't been working much currently...

Also completely unrelated but jisoo is finally having a soloooo omggg I'm so excited!! If I can do well on my methods exam I'm going to consider jisoo's solo as a reward lol!

-bibliii

jinx_58

Bibliii
Make sure you have all the basics down pat, and understand what equations to ise when. Check if your library has any resources like the Oxford Study Buddy or ATARnotes topic tests. I found it really helped me. Understand your formula sheet, and write down any formulas that aren't on there, like the general equation of a sine or cosine function, things that are usueful. Use this when you are studying.

With math, the only way to actually study is by practicing. Practice heaps. Check out the QCAA exam examples. Recycle through different textbook questions - the cambridge one has really good ones. Talk to your school or local librarian and ask if they have year 12 methods resources - it always helps. You could check out the VCAA and HSC past exams, and pick out the ones that are relevant.

Hope this helped,
-jinx_58

Bibliii

jinx_58 Ahh thank you for this, I'll start doing this right away!!

Teo43

Hey guys, be sure to check out QCE Gambit website (https://www.qcegambit.com/) for practice IA2s!!

DumbNerd

So I got confirmed 17/20 for my assignment and I'm so disappointed. I'm gonna make sure to ace the IA3 (cause otherwise I'm dead) so I'd love to help with questions when externals approach. I'm already studying for it. 🤓

Leeshi

I'm still in year 10 so I'm not in a methods class yet, but will be next year. I just can't find the math question thread... So I'll ask it here. Out of linear, exponential, parabola, and quadratics for graphing, which one is best suited for recording the temperature of water every 5 mins (from hot to cold)?

Billzene

Leeshi Water cools proportional to its temperature differential so the diff eq will be dT/dt = -k(Twater - Tenvironment), where k is a constant of proportionality, Twater is temperature of the water after t min and Tenvironment is the temperature of the surroundings

This will integrate to an exponential with the base e so you need an exponential model

sarah99

hey! i'm not sure if anyone will reply in this thread, but i'm really confused about this question for my methods exam.
The equation is y = 2sin (x) - 1, where the domain is from 0 to 3 pi. We were asked what the x-intercepts are.

I understand you re-arrange to get sin(x) = 1/2, so the reference angle is pi/6.
What do you do after this?
They got 4 answers, until 3pi, but I don't understand how they got all of them, and why we getting all these answers?
They are pi/6, 5pi/6, 13pi/6, 17pi/6

PhytoPlankton

sarah99

Hey @sarah99,

Sorry if it's too late but to answer that I'll go through the whole working out. So to summarise the question, it's solving the equation 𝑦 = 2 sin(𝑥)−1 for 𝑥 where 𝑦 = 0, over the domain 0≤𝑥≤3𝜋.
2sin(𝑥)−1=0
sin(𝑥)=1/2
𝑥=𝜋/6 (which is correct with your reference angle you calculated too)

So from there, you need to first draw out or see what x values equal to 𝜋/6 from 0 to 2𝜋 first. So obviously, that would be 𝑥=𝜋/6 in the first quadrant and then 𝑥=5𝜋/6 in the second quadrant (remember, these are quadrants where sin is positive). The other two quadrants in 0 to 2𝜋 don't have values for x since they will be negative.

Now extending this to 3𝜋, you see that you are essentially extending to 180 degrees (or 𝜋). So here you get another two solutions that are in the first and second quadrant as well which will be essentially 2𝜋 plus the first two solutions we got so that will be 𝑥=2𝜋+𝜋/6=13𝜋/6 and 𝑥=2𝜋+5𝜋/6=17𝜋/6.

So yeah all your solutions for 𝑥 will be 𝜋/6, 5𝜋/6, 13𝜋/6 and 17𝜋/6. Since there are two sets of quadrant 1 and 2 from 0 to 3𝜋.

Anyways, hope that helps and let me know if you have any more questions!