math1001: differential calculus (2 Viewers)

[Winston]

Originally posted by JUB JUB

draw the graph....it's just like the question in the book part 5.6 except the graph is different. look at the direction of the graph as x approaches negative infinity.


has anyone done 2iii) or 2 b) ?

hmmm ill try have u done 1a) yet? wat the hell does it mean to plot

and how would u go about that? :S... the book is very vague at explainning it.

 

[Carlito]

Originally posted by Winston
eek how do u do that question Carl?!

I did it by high school methods, lol.

Originally posted by Winston
... the book is very vague at explainning it.

ive read all the relavent sections and can still only do 2 questions on the whole assignment.

 

[Winston]

Originally posted by Carlito
I did it by high school methods, lol.



ive read all the relavent sections and can still only do 2 questions on the whole assignment.

wat does it mean by critical points? :S is that the stat points, with a new wanky Uni maths term implaced?

 

[JUB JUB]

Originally posted by Winston
hmmm ill try have u done 1a) yet? wat the hell does it mean to plot

and how would u go about that? :S... the book is very vague at explainning it.

well i haven't done it. i know what to do, but i can't draw it.
like u sub in z and plot the circle or whatever it is and draw 4 of them, one of each value, 0,1,2,3. but i don't know how to draw the shapes on the 2d plane....
i just started 2 iii, and i am on my 3rd page of working already....is there an easier way of doing this?

 

[Adam]

People people. I have drawn the graph in excel.

Min @ -2, Max @ 0, Min @ 5.

Then at x= +-oo (lol) y = oo

 

[Adam]

Here she is...

 

[famunlau]

Originally posted by JUB JUB
well i haven't done it. i know what to do, but i can't draw it.
like u sub in z and plot the circle or whatever it is and draw 4 of them, one of each value, 0,1,2,3. but i don't know how to draw the shapes on the 2d plane....
i just started 2 iii, and i am on my 3rd page of working already....is there an easier way of doing this?

They are ellipses...centre of 1,3....major axis of 2 and minor axis of 4
for z =0
u should get something like...
z^2 - 4 = (x-1)^2 + (y-3)^2/4
from this ...u need to put into the form of ellipse
1 = (x-h)^2 / a^2 + (y-k)^2/b^2
where a is the major axis, b the minor axis and (h,k) the centre of teh ellipse....
I hope that helps
also z = 3 is undefined....z =1 is a smaller ellipse and z=2 is a point

 

[Winston]

Originally posted by famunlau
They are ellipses...centre of 1,3....major axis of 2 and minor axis of 4
for z =0
u should get something like...
z^2 - 4 = (x-1)^2 + (y-3)^2/4
from this ...u need to put into the form of ellipse
1 = (x-h)^2 / a^2 + (y-k)^2/b^2
where a is the major axis, b the minor axis and (h,k) the centre of teh ellipse....
I hope that helps
also z = 3 is undefined....z =1 is a smaller ellipse and z=2 is a point

LOL how the hell do uno its an ellipsis and having to do it like that? :S

 

[Carlito]

i tried making y the subject... i got like umm.....

y=+- 2(Sqrt[ 4 - (x-1)^2 - z^2 ] + 3)

*shrugs*

having said that, i still have no idea how to draw level curves no matter what i do

 

[Adam]

Aaaah, I got:

y= 2.sqrt[5-x-z]+3

Do we really need the +-, pft?

Edit: Also, how do you do 1)b)ii)?? You can factorise that, or do you just differentiate the crap out of it until it crys for you to stop?

 

[famunlau]

Originally posted by Winston
LOL how the hell do uno its an ellipsis and having to do it like that? :S

The equation has to make some sort of sense to be able to draw a level curve about it....
so it has to be a level curve that represents something...i.e. a circle, square etc...

 

[Carlito]

Umm doesnt an ellipse have to equate to 1 ?

like umm...

(x - h)^2        (y - k)^2
-----------   + -------------     = 1
    a^2             b^2

and what is major axis minor axis.. ???

ugh im so confused

 

[famunlau]

Originally posted by Carlito
Umm doesnt an ellipse have to equate to 1 ?

like umm...

(x - h)^2        (y - k)^2
-----------   + -------------     = 1
    a^2             b^2

and what is major axis minor axis.. ???

ugh im so confused

yeh it does...the first question requires some manipulation....ie divide one side to get the value of 1.....
the major axis is the "radius" along the x axis..
the minor axis is the "radius" along the y axis...
this provides the elliptical level curve...

 

[tooheyz]

how r u people describing the 3d graph man?

 

[JUB JUB]

just say the shape of the base and combine that with the shape of the object.

 

[tooheyz]

Originally posted by famunlau

the major axis is the "radius" along the x axis..
the minor axis is the "radius" along the y axis...
this provides the elliptical level curve...

i thought the minor axis was the diameter of the entire minor axis... or is it just the radius? know what im saying?

 

[famunlau]

Originally posted by Winston
hmmm ill try have u done 1a) yet? wat the hell does it mean to plot

and how would u go about that? :S... the book is very vague at explainning it.

Look if u want some help in maths Winston and everyone else....ask tooheyz....she's the resident mathematician

 

[famunlau]

Originally posted by tooheyz
i thought the minor axis was the diameter of the entire minor axis... or is it just the radius? know what im saying?

its diameter....thanx Tooheyz...cleared things up for me

 

[tooheyz]

its good to be back.

 

[famunlau]

I've only just started.....ROFL