First Year Mathematics A (Differentiation & Linear Algebra) (3 Viewers)

InteGrand · Apr 12, 2016

Re: MATH1131 help thread

Flop21 said:
Oh right, because you can have multiple parametric vector forms for the same line? Because I was getting the signs of my vectors opposite to the answers (since they used A-B).

Yes, the parametric vector form for a given line is not unique. This is why we sometimes say "a" parametric form rather than "the" parametric form.

Flop21 · Apr 12, 2016

Re: MATH1131 help thread

FML

I'm falling behind in maths. I need to catch up on lectures I've missed (due to catching up), but have trouble attending lectures since I don't understand what's going on because I've missed lectures / haven't had time to revise and understand.

So little time for anything tbh.

It's like a horrible cycle that I can't get out of, any advice anyone?

leehuan · Apr 12, 2016

Re: MATH1131 help thread

Flop21 said:
FML

I'm falling behind in maths. I need to catch up on lectures I've missed (due to catching up), but have trouble attending lectures since I don't understand what's going on because I've missed lectures / haven't had time to revise and understand.

So little time for anything tbh.

It's like a horrible cycle that I can't get out of, any advice anyone?

Surely you have lecture recordings on moodle

But the course pack does a reasonable job at filling people in if you ask me

Flop21 · Apr 12, 2016

Re: MATH1131 help thread

leehuan said:
Surely you have lecture recordings on moodle

But the course pack does a reasonable job at filling people in if you ask me

So I should skip this week's lectures as well and spend it catching up? I find myself prioritising studying for tests, so lately I've been just catching up on the upcoming test's material and not wanting to go ahead - but of course class is still speeding along with new crap while I study.

Course pack is really good. Man can't wait to start over next sem, I've learned so much, but kind have stuffed this sem.

leehuan · Apr 12, 2016

Re: MATH1131 help thread

Flop21 said:
So I should skip this week's lectures as well and spend it catching up? I find myself prioritising studying for tests, so lately I've been just catching up on the upcoming test's material and not wanting to go ahead - but of course class is still speeding along with new crap while I study.

Course pack is really good. Man can't wait to start over next sem, I've learned so much, but kind have stuffed this sem.

In advance for the calculus test you probably want to focus on studying for that. Same for algebra. Then when no calculus test is coming up you should catch up on the calculus that you missed.

But maths, well I view it as two seperate courses in algebra and calculus. You treat them seperate until final exam time.

As for missing, well that's probably up to you

Shadowdude · Apr 12, 2016

Re: MATH1131 help thread

Flop21 said:
FML

I'm falling behind in maths. I need to catch up on lectures I've missed (due to catching up), but have trouble attending lectures since I don't understand what's going on because I've missed lectures / haven't had time to revise and understand.

So little time for anything tbh.

It's like a horrible cycle that I can't get out of, any advice anyone?

If it makes you feel any better, I'm in the exact same boat for my subjects now

And to compound it, my supervisor sent me an email, "Hey SD, how's the work going? Let's meet next week to discuss your project"

catch is: i haven't done any work

she's going to kill me

Flop21 · Apr 13, 2016

Re: MATH1131 help thread

Why is it when given some points after finding the cross product of vectors AB and AC, you find the result distance to find the area of the parallelogram?

How does that give you the area of a parallelogram?

InteGrand · Apr 13, 2016

Re: MATH1131 help thread

Flop21 said:
Why is it when given some points after finding the cross product of vectors AB and AC, you find the result distance to find the area of the parallelogram?

How does that give you the area of a parallelogram?

$\noindent Recall that the length of the cross product of two vectors $\vec{a}$ and $\vec{b}$ in $\mathbb{R}^3$ is given by $\left \| \vec{a} \times \vec{b} \right \| = \left \|\vec{a} \right \| \left \| \vec{b} \right \| \sin \theta$, where $\theta$ is the angle between the vectors. This is precisely the area of a parallelogram with side lengths $\left \| \vec{a}\right \|$ and $\left \|\vec{b} \right \|$ with angle $\theta$, as simple trigonometry shows us that $\left \|\vec{a}\right \|\sin \theta$ is the perpendicular height of the parallelogram. See the diagram in this link:$

http://mathinsight.org/cross_product.

Flop21 · Apr 13, 2016

Re: MATH1131 help thread

Okay can someone help me with finding the shortest distance d between a line and a point using vectors/projections??

These questions come up a lot and I'm having trouble doing them, so if anyone could give me a general list of steps of what to do to solve these, that would be great.

So say you get given a point - and it's said the line goes through that point, and is also parallel to a vector given, and you also get another point. They require you to find the projv/vector(the vector made by second point - first point).

Now what do you do from here to find the shortest distance between the line and the second point??

[if it would be easier for me to give a real example let me know]

Shadowdude · Apr 13, 2016

Re: MATH1131 help thread

I reckon draw a diagram and that'll help you out a lot - are you drawing pictures?

Flop21 · Apr 13, 2016

Re: MATH1131 help thread

Yeah but it's always so hard in 3D to actually look at the diagram and have it useful

InteGrand · Apr 13, 2016

Re: MATH1131 help thread

Flop21 said:
Yeah but it's always so hard in 3D to actually look at the diagram and have it useful

It suffices to draw a 2D diagram for that, even if the point and line are in some arbitrary n-dimensional space.

Flop21 · Apr 13, 2016

Re: MATH1131 help thread

InteGrand said:
It suffices to draw a 2D diagram for that, even if the point and line are in some arbitrary n-dimensional space.

do you mean drop the z number and just draw x and y?

InteGrand · Apr 13, 2016

Re: MATH1131 help thread

Flop21 said:
do you mean drop the z number and just draw x and y?

We just need to draw a rough diagram to see what projection vector to take and what lengths to use etc. So we don't need to worry about coordinates for our sketch. Just draw a line with the known point on the line, and the given point above the line, and see which projection vectors and lengths need to be taken.

So basically pictures like in this link: https://en.wikipedia.org/wiki/Vector_projection .

clareh08 · Apr 18, 2016

Re: MATH1131 help thread

If in 2014, the Australias population was 23 246 692, with a growth rate of approximately 1.14%, what was the population in 2015?

Please help! What is the formula and how would you work out this question

Flop21 · Apr 21, 2016

Re: MATH1131 help thread

Why is this true:

Wouldn't it be 1 real zero?

parad0xica · Apr 21, 2016

Re: MATH1131 help thread

Flop21 said:
Why is this true:

Wouldn't it be 1 real zero?

Why do you think it's 1 real zero?

I think we need more info

Flop21 · Apr 21, 2016

Re: MATH1131 help thread

parad0xica said:
Why do you think it's 1 real zero?

I think we need more info

If it's increasing for one part, then decreasing the other part, then there's 1 point where there's a zero since it's begun to decrease. Where's the other zero?

parad0xica · Apr 21, 2016

Re: MATH1131 help thread

Flop21 said:
If it's increasing for one part, then decreasing the other part, then there's 1 point where there's a zero since it's begun to decrease. Where's the other zero?

What if f: (1,4) -> R such that f(x) = 1000 - (x-3)^2? (no zero)

We need more info, can you show what example was above this?

Flop21 · Apr 21, 2016

Re: MATH1131 help thread

parad0xica said:
What if f: (1,4) -> R such that f(x) = 1000 - (x-3)^2? (no zero)

We need more info, can you show what example was above this?

First Year Mathematics A (Differentiation & Linear Algebra) (3 Viewers)

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