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July 22, 2025, 03:00:11 pm

Author Topic: VCE Methods Question Thread!  (Read 5573249 times)  Share 

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Phy124

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Re: VCE Methods Question Thread!
« Reply #360 on: February 29, 2012, 12:36:50 am »
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Oh this one has been killing me all day, I absolutely hate using the Binomial Theorem.

Quote
The first six rows of pascal's triangle are shown below.
(insert Pascals Triangle here)
When is expanded into a polynomial in decreasing powers of x, from left to right, the fifth term is

I think I might have missed the relationship between the Binomial Theorem and Pascal's Triangle.
Would I look at the 5th row and add all the numbers and that is the co-eff of it?

It's a multiple choice from VCAA 2000 if anyone's curious.
also, have a pascal swirl.


Firstly, do you understand how pascal's triangle works? (I'll assume so for now and edit in later if you don't)

If it is to the power of 7 you use the numbers from the 8th row of pascals triangle (If you don't understand why (x + a)0 will correspond to the first row)

Although, you don't need any of this I'll show you how it works for when you have a number rather than a, which will affect the coefficient:

1(x)7(a)0 + 7(x)6(a)1 + 21(x)5(a)2 + 35(x)4(a)3 + 35(x)3(a)4 + 21(x)2(a)5 + 7(x)1(a)6 + 1(x)0(a)7


x7 + 7x6a + 21x5a2 + 35x4a3 + 35x3a4 + 21x2a5 + 7xa6 + a7

Anywho, as "a" isn't a number, you can see the coeffcient of the 5th term is 35

edit: beaten, ah well :P

Consider the function f: (-infinity, -1] -> f(x) = (x-1)/ (x^2 + x + 2)
Find the rule for the inverse function f-1
This is tech-active, yeah?
« Last Edit: February 29, 2012, 12:39:39 am by Phy124 »
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generalkorn12

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Re: VCE Methods Question Thread!
« Reply #361 on: March 02, 2012, 06:45:58 pm »
+1
In probability, if you get questions asking 'how many people arrive at this event', sometimes I get decimal answers such as 556.86 and my teacher tells me to always round down, as 'it's illogical to have .86 of a person'. I'm just wondering if that's what other teachers have said.

Hutchoo

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Re: VCE Methods Question Thread!
« Reply #362 on: March 02, 2012, 10:41:29 pm »
+1
0-o. Anything less than .5 = round down, anything that's .5 or greater = round up?
That's what I've been taught for probability

oliverk94

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Re: VCE Methods Question Thread!
« Reply #363 on: March 02, 2012, 11:18:48 pm »
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wtf.. are you guys up to probability already?

TrueTears

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Re: VCE Methods Question Thread!
« Reply #364 on: March 02, 2012, 11:42:54 pm »
+1
When doing probability sometimes just note you need to round according to "context"

ie, say you are asked to find the minimum number of trials to get a probability greater than a certain limit, in this case, say you end up with 19.223

however if you just rounded down to 19, you'd be wrong, since what if 19 trials does not yield a probability greater than a certain limit? In this case, you must round according to the context of the question and round up!
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kensan

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Re: VCE Methods Question Thread!
« Reply #365 on: March 03, 2012, 03:59:52 pm »
+1
With the graph I know that it doesn't have any x intercepts, but how can I find that out for myself algebraically?
If I let

Don't I get two solutions which and which would just be x=1, -3
I know this is wrong, but why can't I do this?
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brightsky

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Re: VCE Methods Question Thread!
« Reply #366 on: March 03, 2012, 04:07:59 pm »
+1
remember that the modulus of anything is always positive.
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kensan

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Re: VCE Methods Question Thread!
« Reply #367 on: March 03, 2012, 05:14:00 pm »
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remember that the modulus of anything is always positive.
Ahh thanks for reminding me :P Didn't really think it through properly
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kensan

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Re: VCE Methods Question Thread!
« Reply #368 on: March 03, 2012, 06:36:33 pm »
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1)Find the value of p for which the system of equations
3x+2y-z=1
x+y+z=2
px+2y-z=1
has more than one solution.      I'm guessing you use rref somehow? I haven't learnt how to do so in class lol.

2)

Confused about this one, couldn't the axis of symmetry be anywhere?
Thanks!
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Phy124

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Re: VCE Methods Question Thread!
« Reply #369 on: March 03, 2012, 07:51:58 pm »
+3
1)Find the value of p for which the system of equations
3x+2y-z=1
x+y+z=2
px+2y-z=1
has more than one solution.      I'm guessing you use rref somehow? I haven't learnt how to do so in class lol.

2)
(Image removed from quote.)
Confused about this one, couldn't the axis of symmetry be anywhere?
Thanks!
I'll leave question 1 out for someone who will be able to explain it better, but for 2:

Lets take the line "<----> 40m" as the y-axis and the horizontal line at the bottom as the x-axis, so we have the coordinates (10,40) at the upper right corner and have (50,0) in the lower right corner, if you don't understand why, just ask.

This gives us:





Solve for a and b, to give you:





edit: had (0,50) as coordinate
« Last Edit: March 03, 2012, 09:23:51 pm by Phy124 »
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kensan

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Re: VCE Methods Question Thread!
« Reply #370 on: March 03, 2012, 08:18:34 pm »
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Ahhhh i get it! Didn't think of finding 2 points and subbing them in. Thanks man :)
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blank

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Re: VCE Methods Question Thread!
« Reply #371 on: March 03, 2012, 09:09:54 pm »
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hi, i have the 2011 of ti-inspire CAS, with the program that came with it and i dont know how to get 2dps for the graphs i draw when i trace them. the program that came with the grey cas in 2010 automatically goes to 2 dps when i trace graphs. can anyone please help? :S
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abd123

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Re: VCE Methods Question Thread!
« Reply #372 on: March 03, 2012, 10:51:29 pm »
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hi, i have the 2011 of ti-inspire CAS, with the program that came with it and i dont know how to get 2dps for the graphs i draw when i trace them. the program that came with the grey cas in 2010 automatically goes to 2 dps when i trace graphs. can anyone please help? :S


Alright from your black cas 2011, go to the graph page, press menu, press 5 for trace and then press 3 for trace step and changed from automatic and place the value as '1'.


and don't you go to braybrook college :P?
« Last Edit: March 03, 2012, 10:53:08 pm by abd123 »

Planck's constant

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Re: VCE Methods Question Thread!
« Reply #373 on: March 06, 2012, 12:44:10 am »
+4
Use difference of squares



and

Factorised:

Possible to simplify further maybe, but that's enough to be considered factorised.

More than anything, this type of problem is a test of technique.
Therefore when they show you the numbers 50 and 98, what they really want you to see are the numbers 25 and 49.
Accordingly, you take 2 out as a common factor and proceed as follows:

=
=
=


oliverk94

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Re: VCE Methods Question Thread!
« Reply #374 on: March 07, 2012, 09:43:10 am »
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Hey guys I need help trying to graph loge (x-3/2)+4

I tried finding the asymptote by making x-3/2=0, and I get an asymptote at x=3 but when I graph it's at x=1?