VCE Specialist 3/4 Question Thread!

[Hutchoo]

I like solving the domain like this.
-1<_x<_1

-1<_2x<_1 => (make it x again by dividing it all by 2) -1/2<_x<_1/2

[soccerboi]

To sketch the graph y= sec(2x-(pi/2)) , we change it to y=1/ cos(2x-(pi/2)).
Then to find the stationary points, the solutions let cos(2x-(pi/2))=plus minus 1, why?

[paulsterio]

To sketch the graph y= sec(2x-(pi/2)) , we change it to y=1/ cos(2x-(pi/2)).
Then to find the stationary points, the solutions let cos(2x-(pi/2))=plus minus 1, why?

Have a think about it. Let's just say y = 1/A

and A is a number between -1 and 1 inclusive (A = cos(...))

so when will y be smallest? when A = -1

when will y be greatest? when A = 1

[#1procrastinator]

When you integrate a second order DE twice and you have to make a substitution, why is it wrong to keep the initial substitution and use it for the second integration? So if you subbed in U, how come it's wrong to integrate that U again? And how would you get around this (aside from changing back to x's)

Example?

Sorry, forgot about this!

e.g.


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Another question, how would you find an expression for T1 and T2 (tension), in terms of the angle (alpha?) for this (see attached image, it's supposed to be a hanging mass). m=5

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@b^3: How the heck did you do that crazy diagram on page 47?!

[BubbleWrapMan]

When you integrate a second order DE twice and you have to make a substitution, why is it wrong to keep the initial substitution and use it for the second integration? So if you subbed in U, how come it's wrong to integrate that U again? And how would you get around this (aside from changing back to x's)

Example?

Sorry, forgot about this!

e.g.

So you'd get , if you wanted to solved for y you'd need to integrate both sides with respect to x, i.e.:



So you can see that would be problematic without changing it back to x first. If you integrated it with respect to u you'd get a different function:

[VCEstudentguy]

How come if I try to solve the definite integral in the image below using Casio Classpad it comes up as undefined? It's a VCAA question on the 2006 Exam 2 Q3iii.

[meemz]

How come if I try to solve the definite integral in the image below using Casio Classpad it comes up as undefined? It's a VCAA question on the 2006 Exam 2 Q3iii.

not sure, but i tried it on the ti-nspire and it worked
maybe you're putting dx instead of dv or you're not multiplying the 9600 by v, but just typing 9600v

[Hutchoo]

How come if I try to solve the definite integral in the image below using Casio Classpad it comes up as undefined? It's a VCAA question on the 2006 Exam 2 Q3iii.

not sure, but i tried it on the ti-nspire and it worked
maybe you're putting dx instead of dv or you're not multiplying the 9600 by v, but just typing 9600v

Wtf X________________X. My classpad doesn't solve it either.. Classpads are so shit lol. Hope this stuff doesn't happen on the end of year exams :/

[Jenny_2108]

^ You should buy ti-nspire!!! Somtimes Classpad can't solve for combination in methods as well. It'll be disadvantages for you in the maths exams

[Hutchoo]

Easier said than done!
It takes quite a long time to get used to a new calculator. You can't just pick it up and become a super beast.

[Jenny_2108]

Easier said than done!
It takes quite a long time to get used to a new calculator. You can't just pick it up and become a super beast.

From now until the exams, you have 6 weeks.
If you use the new CAS when doing trials during hols, I'm sure you will get used to
It took me 3 days in year 11 to know how to use CAS but you already use Classpad so it will be quicker for you anyway

[VCEstudentguy]

^ You should buy ti-nspire!!! Somtimes Classpad can't solve for combination in methods as well. It'll be disadvantages for you in the maths exams

Yeah I think we discovered yesterday with the Methods question and today with the Spesh question that the TI seems to be superior haha. I think I'll stick with the Classpad though, too late to back away now after years of use.

[nisha]

Easier said than done!
It takes quite a long time to get used to a new calculator. You can't just pick it up and become a super beast.

From now until the exams, you have 6 weeks.
If you use the new CAS when doing trials during hols, I'm sure you will get used to
It took me 3 days in year 11 to know how to use CAS but you already use Classpad so it will be quicker for you anyway

Bear in mind, that means buying a new calculator, then learning its ins and outs.

^^Go to your teacher and ask them why it isn't working. I'm sure there is a way.

[pi]

It might be worth shooting a PM to Paul Sterio about it, he used the Casio in VCE

[Conic]

It might be worth watching some online comparisons between the Calculators and reading through the TI nSpire guides before you decide whether or not to buy the Calculator.