VCE Methods Question Thread!

[lzxnl]

I think you're meant to know that the square root of 2 is roughly 1.4. I may be wrong on that.

[b^3]

I think you're meant to know that the square root of 2 is roughly 1.4. I may be wrong on that.

I kinda agree with this. Whether we're meant to know it or not, it comes in handy if you know that it's around 1.41 and others that are similar. Like Zealous, doing exercises over the year is how I started to remember simple ones. Plus, in the end if it's exam 1 they're (VCAA at least) not going to give you something too complicated.

[Daenerys Targaryen]

For questions like:


How do you show working for 2 marks, without going through the whole substitution method

[b^3]

These aren't 2 mark questions anymore, you just need to show you used the chain rule for the mark

The two mark questions for differentiation questions are when you have to sub a value in (particularly exact angle ones)

If it's a product rule question then it may still be a 2 mark question. It will change sometimes because the exam writers still have to get 40 marks out at the end, so if they're 1 short it may be a 2 while if they're 1 over it may become a 1. Just depends on the year really and which question they decide to be more/less generous on.

For questions like:


How do you show working for 2 marks, without going through the whole substitution method

It's probably best to show the substitution, but as long as you have the and then have the right expression at the end you should be fine. Just remember though, the simpler you make it to read/explain, the easier it is to mark

[joy1010]

hey guys could someone please help me with this question:

Let f'(x)=g'(x)+3, f(0)=2 and g(0)=1
then f(x) is given by:
A. f(x)=g(x)+3x+1
B. f(x)=g'(x)+3
C. f(x)=g(x)+3x
D. f(x)=1
E. f(x)=g(x)+3

[lzxnl]

hey guys could someone please help me with this question:

Let f'(x)=g'(x)+3, f(0)=2 and g(0)=1
then f(x) is given by:
A. f(x)=g(x)+3x+1
B. f(x)=g'(x)+3
C. f(x)=g(x)+3x
D. f(x)=1
E. f(x)=g(x)+3

Integrate both sides
f(x)=g(x)+3x+constant
i.e. f(x)-g(x)-3x=some constant.
Let's find this constant.
x=0
f(0)=2, g(0)=1, 3x=0
so f(0)-g(0)-3x = 2-1-0=1=constant
constant = 1
f(x)=g(x)+3x+1
A

[joy1010]

Integrate both sides
f(x)=g(x)+3x+constant
i.e. f(x)-g(x)-3x=some constant.
Let's find this constant.
x=0
f(0)=2, g(0)=1, 3x=0
so f(0)-g(0)-3x = 2-1-0=1=constant
constant = 1
f(x)=g(x)+3x+1
A

thanks so much

[Kayte]

Hi there could someone me with Question 4F in the 2012 Exam 2

I understand that it takes 20 minutes for the tank to empty and (8(pi)/15) for the liquid to reach h=2 again, but I'm not quite sure why in the solutions they minus 12.2 from 20.

Could someone clear that up for me?

Thanks!

[Zealous]

Hi there could someone me with Question 4F in the 2012 Exam 2

I understand that it takes 20 minutes for the tank to empty and (8(pi)/15) for the liquid to reach h=2 again, but I'm not quite sure why in the solutions they minus 12.2 from 20.

Could someone clear that up for me?

Thanks!

By the time we reach 4F, we have two big pieces of information (from previous sections):
- The liquid height will first decrease to 2 metres after 12.2 minutes (or another way of putting it: the liquid level was above 2 metres for the first 12.2 minutes).
- The liquid height will reach 0 metres after 20 minutes.

Tasmania can only climb down when the depth of liquid is at 2 metres or less. So we need to find the time in which the water is above 0 metres and less than 2 metres (for when the liquid is draining out of the cone).

So we take the 20 minutes it takes to completely empty, and take away the 12.2 minutes in which the liquid was above the 2 metres mark, giving us the amount of time in which the liquid is between 0 and 2 metres.

Then we can add the 8pi/15 on top of that which is the amount of time it takes for the liquid to fill back up to 2 metres (after completely draining).

Hopefully that makes sense!

[lzxnl]

I hate this question This was the one mark I dropped last year because I wasn't thinking properly when I needed to -.-

[papertowns]

Can someone help me and explain how to do this question from the engage practice exam please?

MC Q7. 5 cards are drawn at random from a 52 card deck containing equal numbers of each suit (spades, clubs, hearts, and diamonds) without replacement. The probability that all the cards drawn are of the same suit is:

A: 13C5
B: 4 X 13! X 47!/8! X 52!
C: 52C5 (1/13)^5 (12/13)^47
D: 5C5 (1/13)^5 (12/13)^0
E: (1/13)^5

I'm finding probability reallly hard

[Zealous]

Can someone help me and explain how to do this question from the engage practice exam please?

MC Q7. 5 cards are drawn at random from a 52 card deck containing equal numbers of each suit (spades, clubs, hearts, and diamonds) without replacement. The probability that all the cards drawn are of the same suit is:

A: 13C5
B: 4 X 13! X 47!/8! X 52!
C: 52C5 (1/13)^5 (12/13)^47
D: 5C5 (1/13)^5 (12/13)^0
E: (1/13)^5

I'm finding probability reallly hard

I needed help with that a few months ago. Here's Alwin's post which helped me out with it. Go thumbs up his post if it helps you too =p

Q2  EDIT: thanks nliu! didn't read the q, i worked out choosing 4.. not 5 cards..Okay, so lets SUPPOSE the suit is hearts <3. Find the probability of choosing 5 from the hearts. So:

Now here's the a trick:


Now, what if we had chosen one of the other 4 suits, not just hearts. So then, its:

Pr(choose 4 hearts) + Pr(choose 4 spades) + Pr(choose 4 diamonds) + Pr(choose 4 clubs)

[papertowns]

I needed help with that a few months ago. Here's Alwin's post which helped me out with it. Go thumbs up his post if it helps you too =p

Oh thank you for looking for the post for me! Where do I go to thumbs it up? This makes so much more sense than when my teacher did it....

[papertowns]

Another question!

[ahat]

Another question!

Euler's method, let f(x) = x^1/3, x = 343 and h = 2
Hence f(343 + 2) = f(343) + 2f'(343)
E B

*And what Nliu said*