Math exams sucked. I need help.

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Can anyone tell me the answer to:

a) determine the critical points of the function "g"

b) determine what kind of critical points the function of "g" have.

Funtion "g":

g(x,y)= arctan(x(2nd potens)+y(2nd potens)), (x,y) can be any real number.

I think I cracked up this assignment. Any good ideas? any bad ideas?

[This message has been edited by Nobleman (edited June 10, 2001).]

 

Sorry, I'm going to reply in danish: Nobleman, er det en ligning med to ubekendte? Eller er vi ovre i differentialregning? Det ville være rart, hvis du kunne oplyse hvilket niveau dette er på, da jeg ikke vil virke som komplet idiot og svare på noget universitetsbævl!

 

To Grovflab: Its MM01 course at uni. Its just above MatA in ordinary highscool (danish= gymnasie, handelsskole).


Thanks for the mental support TAL.
With some trouble I can convert it into
Swedish, Spanish, Lithuian, German. Will any of these help TAL

This board has many different people with many different occupations. so I had a faint hope. I'll just wait till monday and harrash my friends at Uni.

 

Sorry, can't help you then. I'm only at level A. (3rd year HHX)

Hope you find out!

But those critical points still sounds like differential....

Edit: Beklager, men jeg kender kun lokal extrema og kritikpunkter med en ubekendt. Men burde du ikke isolere y og derefter diffentiere til g'(x)?

[This message has been edited by Grovflab (edited June 10, 2001).]

 

You are right it is differential. I am just having some major troubles. Never mind. I'll Get the results tomorrow.
I just thought with the average age in here at around 26-27, some of those Grumpy old men might have some advanced math-ability, and could just flick the result out in aminute.

 

Sorry Nobleman, I wasn't here...

Anyway, can you translate the formula into programming code stuff? Or Excell Worksheet formula?

I think you probably need minimum and maximum - with first differential if it is equal to zero. And also that "potens" thing looks as exponential function.

However, I need details, not speculations. I really don't know what do those things you posted really mean.

[This message has been edited by Extremist (edited June 10, 2001).]

 

sorry i wasnt here earlier i think i could have helped

 

Sorry, when I walked into my A'level maths exam 16 years ago I was fully prepared not to understand any questions on the paper let alone produce answers. (A note to anyone studying maths at a lower level and considering taking it on to A'level - do not do it. All the teachers lie to you about it. It is not the same subject at all. Being good at normal maths is absolutlely no gurantee of being good at advanced maths they have nothing in common worth mentioning (although I understand nowadays they are making A'levels so easy that o'level questions from my day are appearing in A'level papers - that's sort of ok in a discussion type subject but not in a science)). Anyway, when I walked out of the exam I decided to do my best to never think of advanced maths again and to put that bizarre world out of my head.

PS fortunatley I did pass the exam which shows miracles do still happen.

 

Hehe Slappy. Its a miracle.

It doesn't matter E. Not now anyway. I went drinking instead. Had a thrill and now I am just gonna sleep on it.
No need to graduate all courses in one try. I love math, can't wait to have the same course one more year.

A song keeps running in my head:
TIme is on my side.

 

I'm pretty good at maths (no errors on last 2 hour test, 1 error on last whole day test).

Show me this in swedish (norwegian would be better, but I should understand swedish) and perhaps I can help.

Edited:

Or is it too late?

[This message has been edited by Mollusken (edited June 11, 2001).]

 

I'll assume it's too late for the exam in question, but to re-phrase the question for those of you who are interested:

a) Determine the turning points (Maxima and Minima) for the function.

b) Determine which it is (max or min) or both presumably.

The function is g(x,y)=arctan(x[squared]+y[squared]) for any real x and y.

arctan from memory is the inverse of tan, from distant trig lessons.

Not having done this for some 15 years, I shall not by the looks of things be the one to solve....

[This message has been edited by Viking (edited June 11, 2001).]

[This message has been edited by Viking (edited June 11, 2001).]

 

Thank you all for the support. I have the answers now.
To those of You interested I can email the solution as an attachment. I don't know Why though its a crazy world.

The solution is to make partial derivate and equal this to 0.
This gives a critical point at (0,0)

second we must make the another partial deriviation to find out what kind of critical ponint it is. Messy stuff where I screwed up.
The local extreme is a relative minimum. For more information on this its in our text book. "calculus" by Adams page 773

I apreciated your support, now I can continue on Retsnimle