VCE Methods Question Thread!

[BubbleWrapMan]

Really?  Thanks for that, so when ever you simplify something in a square root it cancels the square root?  So as you can see for me inspection was easier and cts took me like 5 goes to do cause the fractions was to big and i needed to be precise so what do you suggest i use?

Well, I was mainly trying to convince of the fact that you can always use CTS (since you asked). I recommend the easier method, which is factoring, in most cases.

Also if a question was asked as a trinomial in the form of a quadratic expression but had no =0 could i still use cts and would it still be the same answer if i used inspection?

You should get the same answer from both methods if you do them correctly.

[Only Cheating Yourself]

Well, I was mainly trying to convince of the fact that you can always use CTS (since you asked). I recommend the easier method, which is factoring, in most cases.

You should get the same answer from both methods if you do them correctly.

CTS is factorising isn't it… Also going back to my thread 'thinking like a mathematician' i saw shelden post a thread on maths competitions or something like that anyway the questions there are worded ones like a train was travelling at this speed…. what is this in x …… I struggle with these questions how can i improve?

Thanks

[BubbleWrapMan]

Well, everyone's different, but I tend to improve by learning the theory first.

[lzxnl]

For me, it depends. If it's just one dilation or transformation, you could read it off by the function method.
However, I use the dash method for a more complex series of transformations. For instance, I'm not going to want to do a dilation by factor 4 from x axis, 2 unit translation in positive x direction, dilation factor 2 from y axis, reflection in x axis, translation by 2 units in negative y direction, dilation again by factor 2 from x axis...not doing that by function method

[mackintosh]

For me ,the only error proof way of doing transformation is the 'dash' method ( x' and y'), which holds up under exam pressure and can be done almost without thinking . People can tie themselves in knots with the function method for more complex functions , but for very simple functions checking with the function method (i.e s the resulting function realistic?) is worthwhile I think.

[Orb]

Well, everyone's different, but I tend to improve by learning the theory first.

Have to agree on this, the theory should be the first thing that you learn because it also helps your application to problems!

If you don't know the theory you'll have to search it up and you could always miss a potential loophole or something that may cost you marks!

[BLACKCATT]

Can someone explain what the dash method is? i don't think its in my textbook

[mackintosh]

Can someone explain what the dash method is? i don't think its in my textbook

X' is the x coordinate of the image ( transformed coordinate )  and y' is the y coordinate of the image . For a transformation , eg dilation by factor two in the direction of the x axis followed by a translation by one unit in the positive direction of the x axis . Then you would write x'=2x+1 as each original x coordinate is doubled and moved one to the right . Rearrange to make x the subject . (X'-1)/2=x. Substitute this into your f(x) function for x. Eg if y=x^2 then y'=(x'-1)^2/4 . Remove the dashes . That's pretty much it . Just remember that x' and y' are the coordinates of the transformed point ( you can 'undo' transformations using this method also )

[brightsky]

Alternatively, you can just remember the following:
- To dilate y = f(x) by a factor of k from the x-axis, replace y with y/k.
- To dilate y = f(x) by a factor of k from the y-axis, replace x with x/k.
- To reflect y = f(x) in the x-axis, replace y with -y.
- To reflect y = f(x) in the y-axis, replace x with -x.
- To translate y = f(x) k units in the positive direction of the x-axis, replace x with x - k.
- To translate y = f(x) k units in the positive direction of the y-axis, replace y with y - k.

I never used the dash method in any of my exams, but if you find that the dash method is easier, by all means stick to it. The worst thing you can do is mix and match; just stick to one technique and use it for all transformation questions.

[Only Cheating Yourself]

Have to agree on this, the theory should be the first thing that you learn because it also helps your application to problems!

If you don't know the theory you'll have to search it up and you could always miss a potential loophole or something that may cost you marks!

Theory, you guys mean the content?  Can i know the content by teaching my self?

[BubbleWrapMan]

Well, I mean things like techniques and concepts - e.g. you need to be able to solve quadratics before you can do worded questions involving solving quadratics.

[spectroscopy]

the 3/4 textbook has some notation i havent seen before can someone please clarify

when its talking about set difference of two sets A and B, and how its denoted A\B, it says

A\B={x:x is an element of A, x isnt an element of B }

what does the x: mean exactly? (you can sorta tell) and also when do i use it?
cheers

[Only Cheating Yourself]

Need help with a question.

Rerrange and solve the the following

x^2=10-x
            /2

To solve for x, don't we need to make it a linear equation so we can solve for x? 

My thought process was that i can use the 'fixed point iteration' rule but first i need to get into ax^2bx+c, which i'm finding trouble with.

[hobbitle]

Multiply both sides by two then rearrange as a quadratic.
2x^2 + x - 10 = 0
Then use quadratic formula (do you know that yet? Sorry not familiar with the 1/2 syllabus) or solve using another method you know.

[Only Cheating Yourself]

Multiply both sides by two then rearrange as a quadratic.
2x^2 + x - 10 = 0
Then use quadratic formula (do you know that yet? Sorry not familiar with the 1/2 syllabus) or solve using another method you know.

Thanks and i don't i have but i used inspection and got the answer….  What the hell was i doing?  I actually did this but i used the fixed point iteration method which was no help.

So when ever we want to solve for x when there its a quadratic equation we must use the null factor law?