'Stupid' Exam Questions

[psyxwar]

It's never too late turn it around (welp, unless the exam is over, but that's another matter ). Don't just crank out questions - VCAA are sneaky, and while they may put in questions with similar concepts as earlier exams, they will never be the same question.

You're much better off doing your best to see why the theory in the top range questions work. If you can understand how to answer those top range questions theoretically, you're in a good place to tackle your exam.

Adendum: "It's never too late to turn it around", but DON'T do questions that you don't have WORKED SOLUTIONS for if you're a day away from the exam. If you don't know how to do the question, and can't find a way of figuring it out, you will stress beyond belief.

Certainly! Just make sure to include that intermediate step (where you distinctly show you're multiplying by the chain) so the examiners can see you've applied the chain rule.

Note, you have derived that wrong, but I'm leaving that to it's late and you're tired.

thanks, yeah I'm just fried

[keltingmeith]

I've seen some people start their answers with a line for example "using the quotient rule" or "for the inverse swap x and y". Is this necessary or just a waste of time?

It certainly shows the examiner that you clearly know what you're doing, in case they can't understand your working. However, if you're clear in your working out, you don't need to do it - just make sure the examiner can see what you're doing by not skipping too many steps.

[Phy124]

I've seen some people start their answers with a line for example "using the quotient rule" or "for the inverse swap x and y". Is this necessary or just a waste of time?

I never wrote things like "using the quotient rule" and don't deem it necessary.

However, I did write "for the inverse swap x and y" or something similar and generally tell people to do so. With this being said, I can't recall if it is necessary, but it's probably outlined in the assessor reports or w/e they're called and would be dependent on how you formulate your solution.

For example, I'm almost certain you would be deducted marks if you were finding the inverse (take for example) and you began your solution like this:





...

Rather than:



To find the inverse swap and :



...

[abeybaby]

Definitely need to include the line "For inverse, swap x and y", because otherwise your lines are not true (as Phy124 said above), but yes, lines such as "by the quotient rule" aren't always necessary (but I included them on exam 1 because I always struggled to generate 2 marks out of a simple differentiation question).

Also agree with Valyria. A function is made of a rule and domain. If asked to find a 'function' you need both elements. If you're only asked to find one of these (such as find the RULE for f^-1(x)), then you only need to write that one.

Also, for f(g(x)), the domain is always the domain of g. Since f and g both have their rules and domains defined as part of their function, then if the range of g is not a subset of the domain of f, then the entirety of f(g(x)) DOES NOT EXIST. It's not as though f(g(x)) exists over a restricted domain, no. If you need to restrict the domain of g to get the function to work, then you can no longer call it g(x) and hence f(g(x)) does not exist. There would be some other function with the same rule as g, but a different domain for which the composition would work, but not for f(g(x)). Hence, if f(g(x)) exists, then the domain is always g(x).

But all the rest is super super valuable advice, very helpful post

[chocolatechipcookies]

1. So if we can't write in calculator notation, how do we show normCdf, normPdf, invNorm etc..? because they don't really have 'formulas' as we just type them into our calculator

2. If we have to sketch graphs like y=e^x+(-e)^-x or something (in Exam 1), how would we know what to do?

[chocolatechipcookies]

Is it better to do multiple choice or extended response first for Exam 2?

[Blondie21]

alright this is probably a 'stupid' q so I am glad that there is a thread loool

when finding the derivative of something, is this the correct mathematical notation
y = x²
(x²)

=2x

also, say if I wanted to sub in 3 into that derivative, how would I signify it? ATM I just write 'sub in x=3' on the side. Do we need to signify it or can we just write

= 6

?

sorry if that didn't make sense lol

[abeybaby]

1. So if we can't write in calculator notation, how do we show normCdf, normPdf, invNorm etc..? because they don't really have 'formulas' as we just type them into our calculator

2. If we have to sketch graphs like y=e^x+(-e)^-x or something (in Exam 1), how would we know what to do?

If you need to use normcdf or something like that, all you need to specify is the name of the distribution and the parameters which define it. So you would say something like:
Normal, mu=7, sd=2. Therefore, Pr(X>4)=.....

or

Binomial, n=10, p=0.3. Therefore Pr(2<X<7)=.....

And you're not going to get something that's very unfamiliar in exam one, but it's a good tactic to think about addition of ordinates, and find things like stationary points for difficult/confusing graphs.

alright this is probably a 'stupid' q so I am glad that there is a thread loool

when finding the derivative of something, is this the correct mathematical notation
y = x²
(x²)

=2x

also, say if I wanted to sub in 3 into that derivative, how would I signify it? ATM I just write 'sub in x=3' on the side. Do we need to signify it or can we just write

= 6

?

sorry if that didn't make sense lol

Almost correct, the line that says (x²) is mathematically incorrect, and actually doesn't need to be there. Just go straight from your first line to your third line. And if you want to sub in a number, say something like:

When x=3, dy/dx=6.
Also, don't doubt yourself No questions are stupid. Seriously, don't ever hold a question back for fear of being ridiculed. Good luck

[keltingmeith]

1. So if we can't write in calculator notation, how do we show normCdf, normPdf, invNorm etc..? because they don't really have 'formulas' as we just type them into our calculator

2. If we have to sketch graphs like y=e^x+(-e)^-x or something (in Exam 1), how would we know what to do?

1. Believe it or not, they do have formula. However, I cannot articulate in any way better than Stonecold has in this thread. I suggest giving it a read, and if you're still unsure, say what you're specifically unsure about and I can offer some more help.

2. VCAA should not expect you to sketch something so tricky on exam 1 - if you do get it, I'd sketch the graph by addition of ordinates. You can find a video on how to do addition of ordinates here, if you're still unsure after watching it, give us a shout.

Is it better to do multiple choice or extended response first for Exam 2?

If you look through the first few questions, you can see an answer I've supplied for this.

alright this is probably a 'stupid' q so I am glad that there is a thread loool

when finding the derivative of something, is this the correct mathematical notation
y = x²
(x²)

=2x

also, say if I wanted to sub in 3 into that derivative, how would I signify it? ATM I just write 'sub in x=3' on the side. Do we need to signify it or can we just write

= 6

?

sorry if that didn't make sense lol

Okay, notation questions like this are very common. Writing is so common, you often forget what you're doing/actually saying. You see, is an operator. When this operator is applied to a function (in this case, y), we know that we want to differentiate this function.

With this in mind, this means that when we write , this is just a neater way of writing . From this, if you write , since , this is just like writing or - which you know is not what we want to find.

You have two different options you can use - you wrote one, , or you can write .

Subbing in is fine the way you've done it, abeybaby's method is how I used to do it in methods.

[abeybaby]

Is it better to do multiple choice or extended response first for Exam 2?

I personally did extended response first, because if you run out of time, you can guess MC, but you can't guess ER. But that was just my preference.

[keltingmeith]

Also, don't doubt yourself No questions are stupid. Seriously, don't ever hold a question back for fear of being ridiculed. Good luck

Just thought I'd quote this - it's the entire point of the thread! Don't stress, guys. (also stealing for the first page. ;P )

[Escobar]

Do we have to simplify indices/have positive indices/use square root signs
especially when differentiating
eg
(2x-5)^(-3/2)

[speedy]

When solving trig equations, are there ever marks for fiddling with the domain, like this:

Spoiler

If so, is that the correct way of doing it?

[Escobar]

also, do we need to know how get general solutions for trig questions in exam 1?

[keltingmeith]

Do we have to simplify indices/have positive indices/use square root signs
especially when differentiating
eg
(2x-5)^(-3/2)

Definitely not. We often like to show things with positive indices, but the answer is still right if you don't "simplify". Particularly for differentiation questions, leaving indices as negative and not including square root signs is in your favour.

When solving trig equations, are there ever marks for fiddling with the domain, like this:

Spoiler

If so, is that the correct way of doing it?

Depends on the marks given in the question - however, since it's a required step for finding the solution, I'd say yes. The way you've done it looks fine - I do it a different way, but we get the same answer, and your method makes intuitive sense. Only thing is that mathematically, your notation is wrong. Instead of writing x in the middle, write (the angle of the circular function).

also, do we need to know how get general solutions for trig questions in exam 1?

You need to know how to give an answer in terms of a general solution. You can either remember the formula in your textbook, OR derive them yourself. Here you can find a guide by TrueTears on how to derive them yourself.