general UNSW chit-chat (2 Viewers)

[Forbidden.]

回复: Re: 回复: Re: general UNSW chit-chat

woo, high 5 man!

Maybe i actually see you and find out who u are, lol!

What tute u in? Im on wednesday 10am in elec eng 225.

lol i used to have a math1131 algebra tute in that room and my tutor looks like that NAPOLEON DYNAMITE guy.

nope, i dont have math2019 tute that time.
mine is in that old MAN building, just as dusty as elec enginering building.
maybe perhaps i should change it to that time and we can throw paper aeroplanes around and talk shit about that cunt in front who like gets 10/10 in tests?
ahahaha kidding.

 

[Omium]

Re: 回复: Re: 回复: Re: general UNSW chit-chat

lol i used to have a math1131 algebra tute in that room and my tutor looks like that NAPOLEON DYNAMITE guy.

nope, i dont have math2019 tute that time.
mine is in that old MAN building, just as dusty as elec enginering building.
maybe perhaps i should change it to that time and we can throw paper aeroplanes around and talk shit about that cunt in front who like gets 10/10 in tests?
ahahaha kidding.

so your the dude that keeps doing that to me ? :angry:

 

[hectic18]

Re: 回复: Re: 回复: Re: general UNSW chit-chat

lol i used to have a math1131 algebra tute in that room and my tutor looks like that NAPOLEON DYNAMITE guy.

Stephen Howe?

I was in that tute as well! hahah he's a solid tutor

 

[Forbidden.]

回复: Re: 回复: Re: 回复: Re: general UNSW chit-chat

so your the dude that keeps doing that to me ? :angry:

Nah I can recognise the faces of everyone in my tutorial and I'm sure you weren't in any of mine. :uhuh:

Stephen Howe?

I was in that tute as well! hahah he's a solid tutor

hahaha yeah thats him the shy guy but he was better than my calculus tutor.
hes the only maths tutor i had who isnt a lecturer but a research student.

 

[Omie Jay]

so thats whats happening to lib-lawn???

 

[STx]

According to our twitter page :
Remember when I said we were just replacing some pipes? Apparently we may, in fact, be resurfacing the Library Lawn with fresh turf. Maybe.

 

[Omie Jay]

...so who wants to teach me integration, ODE's, and how to use Maple for math1231 maple test???

 

[Forbidden.]

...so who wants to teach me integration, ODE's, and how to use Maple for math1231 maple test???

integration in math1231 takes practice ... practice!!! do the tutorial problems man!!
ODEs, same deal ... but i havent got around modelling with ODEs, thank god they never appeared in session 2 final exam.
when is your maple test? i got 14/15 because i provided the mostly correct code even with many horribly wrong answers BAHAHAHAHAHAHHA!!!
for-while loops or whatever it was fucks up many people in the test.

specifics would be nice.

 

[Omie Jay]

hahaha at maple. My maple test is on monday, calc class test on ode's and some integration is on thurday.

Um..ODE's in general? lol im way to lazy, which is really annoying, concentration span of a amoeba..

eg: Solve the differential eqn: y*root(2x^2 +3)*dy + x*root(4-y^2)*dx = 0
given that y = 1 when x = 0.

I get up to dy/dx = [-x*root(4-y^2)]/[y*root(2x^2 +3)], then what next? I integrate both sides getting y = something, how to find something?!

Maple says that something is -sqrt(4-y)/(y*sqrt(2*x^2+3))+2*x^2*sqrt(4-y)/(y*(2*x^2+3)^(3/2))

then gotta sub in values of y and x, but how do i get that something?!

 

[Omie Jay]

find general soln of y"+8y'+16y = 0

 

[Omie Jay]

and whats the thing which u have to do reverse product rule for?

 

[Iruka]

eg: Solve the differential eqn: y*root(2x^2 +3)*dy + x*root(4-y^2)*dx = 0
given that y = 1 when x = 0.

I get up to dy/dx = [-x*root(4-y^2)]/[y*root(2x^2 +3)], then what next? I integrate both sides getting y = something, how to find something?!

Maple says that something is -sqrt(4-y)/(y*sqrt(2*x^2+3))+2*x^2*sqrt(4-y)/(y*(2*x^2+3)^(3/2))

then gotta sub in values of y and x, but how do i get that something?!

It is a separable equation. You rearrange the equation to get all the x's on one side and all the y's on the other. Then you integrate both sides, add a constant of integration, and substitute in the particular values you were given to evaluate the constant of integration.

 

[Iruka]

find general soln of y"+8y'+16y = 0

First solve the characteristic equation r^2 + 8r + 16=0.

The general solution is y=Ae^(r_1x) + Be^(r_2x),

where r_1 and r_2 are the two solutions to the characteristic eqn, and A and B are constants.

Except that in this case, you have only one solution, cause r^2 + 8r + 16 is a perfect square. Since you should have 2 linearly independent solutions to a second order ODE, you can find another solution by taking the first one and multiplying it by x.

So the solution is y = (A+Bx) e^(-4x)

 

[Iruka]

and whats the thing which u have to do reverse product rule for?

I suspect that you are talking about an integrating factor?

 

[Omie Jay]

I suspect that you are talking about an integrating factor?

If that involves doing the product rule in reverse, then yes.

And thanks for all the help!!!

 

[Iruka]

As far as the DEs stuff in first year goes, I think that there are only four techniques that you need to know:

1) Solving second order linear ODEs using the characteristic equation. You should know how to deal with all three sub-cases - 2 distinct real roots, repeated roots and complex roots. You also have to know how to deal with homogeneous and inhomogeneous equations. This is probably the largest part of the topic, simply because there are so many different cases and subcases.

2) Separable equations.

3) Integrating factors.

4) Exact equations. (Do they still do exact equations?)

 

[Omie Jay]

integration in math1231 takes practice ... practice!!! do the tutorial problems man!!
ODEs, same deal ... but i havent got around modelling with ODEs, thank god they never appeared in session 2 final exam.
when is your maple test? i got 14/15 because i provided the mostly correct code even with many horribly wrong answers BAHAHAHAHAHAHHA!!!
for-while loops or whatever it was fucks up many people in the test.

specifics would be nice.

Any general tips for the for-while loops question? And the geom3D question too:

A(1,2,3), B(-2,3,4), C(1,3,2), L1 is line thru A and B, P1 is plane thru C with normal (1,-2,1), P2 is plane of eqn x + y + z = 1, L2 is line of intersection of P1 and P2.
Find (in rads, 10 sig fig) angle between L1 and L2, and find distance between L1 and L2.

 

[Omie Jay]

before tomorrow plx

 

[uhawww]

man if they respond, they respond - don't get pushy

 

[Forbidden.]

回复: Re: general UNSW chit-chat

ah, math1231 people are getting unsettled.
but then i wouldnt do math1231 or anything during summer whether i fail or not. i would miss out alot. i stress this to myself alot.
this was my motivation not to fail.

but omie jay dude!
how can you not solve 2nd order homogenous ODEs?

its just a matter of solving like a quadratic and the solution is in various forms of exponentials as Iruka caringly explained

As far as the DEs stuff in first year goes, I think that there are only four techniques that you need to know:

1) Solving second order linear ODEs using the characteristic equation. You should know how to deal with all three sub-cases - 2 distinct real roots, repeated roots and complex roots. You also have to know how to deal with homogeneous and inhomogeneous equations. This is probably the largest part of the topic, simply because there are so many different cases and subcases.

2) Separable equations.

3) Integrating factors.

4) Exact equations. (Do they still do exact equations?)

yes they still teach exact equations from my experience in session 2 2008, im assuming the separable ODE must satisfy the conditions that the partial derivative d²H/dxdy = d²H/dydx if i remember correctly.

Any general tips for the for-while loops question? And the geom3D question too:

A(1,2,3), B(-2,3,4), C(1,3,2), L1 is line thru A and B, P1 is plane thru C with normal (1,-2,1), P2 is plane of eqn x + y + z = 1, L2 is line of intersection of P1 and P2.
Find (in rads, 10 sig fig) angle between L1 and L2, and find distance between L1 and L2.

Watch your signs like greater than or less than when meeting conditions in for-while loops.

e.g.
if it asks you to compile a piece of code to generate the first number (like according to a formula) which is LESS than 1 milllionth, write code that must tell Maple to keep cycling through numbers WHILE it is GREATER than 1 milllionth
(which means it will cease to continue once it has met the condition the number is LESS than 1 millionth)

and what do you know, you got the Sample A worksheet!!!
my code below:

Question 4
> restart;
> with(geom3d):
> point(A,[1,2,3])oint(B,[-2,3,4])oint(C,[1,3,2]):
> line(L1,[A,B]):
> plane(P1,[C,[1,-2,1]]):
> plane(P2,x+y+z=1,[x,y,z]):
> intersection(L2,P1,P2):
> evalf(FindAngle(L1,L2),10);

the angle should be 0.5494672456
and the distance should be 17√6 / 18

man if they respond, they respond - don't get pushy

lol ive been playing metal gear solid and out on mayhems, paintballing, sunburnt, etc...