First Year Mathematics A (Differentiation & Linear Algebra) (6 Viewers)

Mr_Kap · Jun 9, 2016

Re: MATH1131 help thread

SpiralFlex said:
^ Technically there is a minimum mark for MATH for higher version courses in second year.

lucky im not doing math next year lol.

Flop21 · Jun 9, 2016

Re: MATH1131 help thread

What's the point of the cross product?? (other than finding area of parallelogram/triangle or whatever)

Flop21 · Jun 9, 2016

Re: MATH1131 help thread

Mr_Kap said:
oh good, yeh i already knew about 70 WAM lol, i though a minimum math mark was needed or some shit. i may not care about honours year anyway and get dropped to science/comp sci.

nah nah. i can't answer ANY OF THE q4. ALSO, i dont know how to integrate...and i dont have time to study that right now so yeh. ive even forgotten 2u integration lel.

seriously though. it feels like im not even taking math this sem...apart from those 4 days all up i studied for class tests...and the 2 days i did maple.

Yeah I learned integration by parts and u-sub today, and i've found it's something you really need to practice over a while.

But since I know the raw basics, hoping I can wing the integration in the exam.

InteGrand · Jun 9, 2016

Re: MATH1131 help thread

Flop21 said:
What's the point of the cross product?? (other than finding area of parallelogram/triangle or whatever)

It has applications in areas outside of mathematics, like physics (torque for instance is a cross product).

Here's the section of the Wikipedia link on cross product about its applications: https://en.wikipedia.org/wiki/Cross_product#Applications .

Flop21 · Jun 9, 2016

Re: MATH1131 help thread

If anyone has a summary of the formulae we must memorise off our heads, that'd be great. E.g. projection

iforgotmyname · Jun 10, 2016

Re: MATH1131 help thread

Mr_Kap said:
oh good, yeh i already knew about 70 WAM lol, i though a minimum math mark was needed or some shit. i may not care about honours year anyway and get dropped to science/comp sci.

nah nah. i can't answer ANY OF THE q4. ALSO, i dont know how to integrate...and i dont have time to study that right now so yeh. ive even forgotten 2u integration lel.

seriously though. it feels like im not even taking math this sem...apart from those 4 days all up i studied for class tests...and the 2 days i did maple.

lucky your not doing any physics, thats where all the maths is at

leehuan · Jun 10, 2016

Re: MATH1131 help thread

integral95 said:
I pretty much just rote learned that part lol, it's always the same type of computation.

It actually made sense to me when I was helping a RL MATH1131 friend...

Flop21 said:
This helps:

if AB = I, then B=A^-1

Basically.
________________

...

You guys make maths look harder than even I do

Flop21 · Jun 10, 2016

Re: MATH1131 help thread

How do I do (if there's any rules I should know when doing these questions pls state them, very helpful thanks) ?

Flop21 · Jun 10, 2016

Re: MATH1131 help thread

How do I find the cartesian equation for a plane, given the cross product??

Flop21 · Jun 10, 2016

Re: MATH1131 help thread

What's this formula??? It's using it to find the min distance between a point and plane. But I thought you used the projection formula?

iforgotmyname · Jun 10, 2016

MATH1131 help thread

Flop21 said:
What's this formula??? It's using it to find the min distance between a point and plane. But I thought you used the projection formula?

This is the distance formula, finds the length of projection

Flop21 · Jun 10, 2016

Re: MATH1131 help thread

iforgotmyname said:
This is the distance formula, finds the length of projection

Oh sugar did not know that existed thanks.

Flop21 · Jun 10, 2016

Re: MATH1131 help thread

iforgotmyname said:
This is the distance formula, finds the length of projection

Can you or someone else please explain the formula? Just what each part is? E.g. what is that first vector... and what is n?

InteGrand · Jun 10, 2016

Re: MATH1131 help thread

Flop21 said:
Can you or someone else please explain the formula? Just what each part is? E.g. what is that first vector... and what is n?

$\noindent The vector $\overrightarrow{PA}$ is a vector connecting a point on the plane and the point whose distance from the plane we are finding. The vector $\bold{n}$ is a normal to the plane.$

Flop21 · Jun 10, 2016

Re: MATH1131 help thread

InteGrand said:
$\noindent The vector $\overrightarrow{PA}$ is a vector connecting a point on the plane and the point whose distance from the plane we are finding. The vector $\bold{n}$ is a normal to the plane.$

Perfect thanks.

Flop21 · Jun 10, 2016

Re: MATH1131 help thread

Flop21 said:
How do I do (if there's any rules I should know when doing these questions pls state them, very helpful thanks) ?

BUMP

InteGrand · Jun 10, 2016

Re: MATH1131 help thread

Flop21 said:
How do I do (if there's any rules I should know when doing these questions pls state them, very helpful thanks) ?

$\noindent We have$

$\begin{align*}\left(A^T A\right)^{-1} \left(A^T A\right)^T &= A^{-1} \underbrace{\left(A^{T}\right)^{-1} A^T}_{=I} \left(A^T\right)^T \\ &= A^{-1} A \\ &= I.\end{align*}$

$\noindent We made use of the rules $\left(XY\right)^{-1} = Y^{-1}X^{-1}$ where $Y$ and $X$ are invertible matrices, the fact that $\left(XY\right)^{T} = Y^T X^T$, $\left(X^{T}\right)^{T} = X$, and that if $X$ is invertible, then $X^{T}$ is too (as well as associativity of matrix multiplication of course).$

leehuan · Jun 10, 2016

Re: MATH1131 help thread

This thread is now redundant for at least one sem 1 break...

(@Flop if you make a 1231 thread please call it a 12x1 thread so that it is friendly to me too pls)

Flop21 · Jun 10, 2016

Re: MATH1131 help thread

leehuan said:
This thread is now redundant for at least one sem 1 break...

(@Flop if you make a 1231 thread please call it a 12x1 thread so that it is friendly to me too pls)

Unfortunately looks like I'll be stuck in this thread for another sem...

KILL ME

Red_of_Head · Jun 10, 2016

Re: MATH1131 help thread

Hope everyone went well, there's always next semester if you didn't.

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