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Author Topic: VCE Methods Question Thread!  (Read 6216625 times)  Share 

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keltingmeith

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Re: VCE Methods Question Thread!
« Reply #6750 on: November 04, 2014, 06:09:16 pm »
+1
I thought for the normal equation we had to make it equal to zero? And tangent was y= blah blah
The normal is simply perpendicular to the tangent.

IndefatigableLover

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Re: VCE Methods Question Thread!
« Reply #6751 on: November 04, 2014, 06:41:03 pm »
0
Hey guys, how would you solve for m?
Well how does a log normally exist? The inside bit has to be greater than zero right? So essentially you want to make the inside bit greater than zero by taking certain values of 'm'. Now the answer (as you'd know is m>3), as this is because if you sub in m=3, you'll find the inside bit equals 1 and when the inside bit equals 1, you get 0 (which doesn't fit the rule). Now normally people would do m>0 but because a normal log isn't disjointed but is smooth infinitely after the asymptote, you'll come across this problem at m=3 (since you get undefined as your answer) hence why m>3.

Just really an application of log laws really :P

The normal is simply perpendicular to the tangent.
Adding on, the normal can be calculated by:
, where m=gradient of tangent

Camo15

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Re: VCE Methods Question Thread!
« Reply #6752 on: November 04, 2014, 06:46:00 pm »
0
Would anyone be able to give C a crack?  I got what I thought was right but the answers disagree


sparksfly

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Re: VCE Methods Question Thread!
« Reply #6753 on: November 04, 2014, 06:58:46 pm »
0
Hey guys
Can someone please help me with general solutions? I don't really understand how to use the formula- i usually just find 1 or 2 solutions and add 2pi etc depending on the unit circle- but sometimes when I do it like this I get it wrong... Is there a way to remember these formulas and how to use them?

Help will be much appreciated   ;D

keltingmeith

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Re: VCE Methods Question Thread!
« Reply #6754 on: November 04, 2014, 07:01:05 pm »
+1
Hey guys, how would you solve for m?

On top of Indefatigable's explanation, we can go algebraically:



So, m>3.

strawberries

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Re: VCE Methods Question Thread!
« Reply #6755 on: November 04, 2014, 07:01:42 pm »
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Question 4 of 2012 VCAA Exam 2

Given that g is a differentiable function and k is a real number, the derivative of the composite function g(e^(kx)) is:

The answer is:
kg'(e^(kx))e^(kx)

but I don't get how? :(

I always get confused on questions like this
VCE '15
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Kaleidoscope

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Re: VCE Methods Question Thread!
« Reply #6756 on: November 04, 2014, 07:02:29 pm »
0
Well how does a log normally exist? The inside bit has to be greater than zero right? So essentially you want to make the inside bit greater than zero by taking certain values of 'm'. Now the answer (as you'd know is m>3), as this is because if you sub in m=3, you'll find the inside bit equals 1 and when the inside bit equals 1, you get 0 (which doesn't fit the rule). Now normally people would do m>0 but because a normal log isn't disjointed but is smooth infinitely after the asymptote, you'll come across this problem at m=3 (since you get undefined as your answer) hence why m>3.

Just really an application of log laws really :P

Gotcha, thanks so much! :)
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Reus

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Re: VCE Methods Question Thread!
« Reply #6757 on: November 04, 2014, 07:02:54 pm »
+4
Pr(screwed for methods)=1
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paulthegreen

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Re: VCE Methods Question Thread!
« Reply #6758 on: November 04, 2014, 07:04:32 pm »
0
Would anyone be able to give C a crack?  I got what I thought was right but the answers disagree

I got

Reus

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Re: VCE Methods Question Thread!
« Reply #6759 on: November 04, 2014, 07:12:20 pm »
0
How does one even do these...  :'(
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keltingmeith

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Re: VCE Methods Question Thread!
« Reply #6760 on: November 04, 2014, 07:22:32 pm »
+3
How does one even do these...  :'(

a)

b)

c)

The last part I skipped a couple of steps done in part b.

Camo15

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Re: VCE Methods Question Thread!
« Reply #6761 on: November 04, 2014, 07:33:54 pm »
0
I got


Ahk, yeah that must be the right answer (same as solutions)

Would you be able to quickly explain how you got it? I got the same except I had (x-1)^2 at the bottom instead of just (x-1)

keltingmeith

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Re: VCE Methods Question Thread!
« Reply #6762 on: November 04, 2014, 07:34:50 pm »
+6
Can someone clarify the following names for probability distributions?
I only know of the three by their CAS name, lol.

1.Binomial
2. Normal
3. Probability density function (the one with integration)

BUT some questions call it the following (and I get confused when they don't tell you how it's distributed)
1. Continuos random variable
2. Discrete random variable
3. Probability function

Am I right in saying continuos = normally distributed
Discrete = binomial
Probability function = probability density function?

Also, are there any other types we need to know in Methods?

Nope in all accounts, sorry. :P

A random variable is a special type of variable whose value is determined at random.

A continuous random variable is ANY random variable defined by the area under a function.
A discrete random variable is ANY random variable defined by discrete data (i.e x=0,1,2,...)
A probability function is what tells you the probability of getting particular values for your random variable.

A binomial random variable is a type of discrete random variable, with probability function . This type of probability function is also called a probability mass function, or PMF.

A normal random variable is a type of continuous random variable, with probability function , where is the mean and the variance. This type of probability function is also called a probability density function, or PDF.

Reus

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Re: VCE Methods Question Thread!
« Reply #6763 on: November 04, 2014, 07:37:11 pm »
0
a)

b)

c)

The last part I skipped a couple of steps done in part b.
Thank you so much!! However I don't understand b :/
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GeniDoi

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Re: VCE Methods Question Thread!
« Reply #6764 on: November 04, 2014, 07:39:39 pm »
+2
Thank you so much!! However I don't understand b :/

I'm posting a more graphical approach I did using pen and paper, should be up in a min or 2

EDIT:




Eh, didn't turn out nicely from doc scanner but should be legible  :P
« Last Edit: November 04, 2014, 07:43:59 pm by GeniDoi »
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