Join TSR now and get all your revision questions answeredSign up now
    • Thread Starter
    Offline

    15
    ReputationRep:
    Sorted
    • Political Ambassador
    Offline

    3
    ReputationRep:
    (Original post by james22)
    I have a suface in R^3 defined by F(x,y,z)=0 where

    F(x,y,z)=(z^2-x^4-a^2)(Y62-x^4-a^2+z^2)

    I need to find the unit normal at (0,0,a)

    I found the normal at this point and got (0,0,0) which isn't helpful. Is this right? If so what does it mean?
    Post your working. I'm not sure what Y62 means btw.
    • Thread Starter
    Offline

    15
    ReputationRep:
    (Original post by Indeterminate)
    Post your working. I'm not sure what Y62 means btw.
    Typo

    I've just put it into wolfram alpha

    http://www.wolframalpha.com/input/?i=gradient+%28z^2-x^4-a^2%29%28y^2-x^4-a^2%2Bz^2%29

    and when I put (0,0,a) into the gradient I get (0,0,0).
    • Thread Starter
    Offline

    15
    ReputationRep:
    Ignore this now, I made a huge mistake earlier in the question which makes this question obsolete. Sorry
    • Political Ambassador
    Offline

    3
    ReputationRep:
    (Original post by james22)
    Typo

    I've just put it into wolfram alpha

    http://www.wolframalpha.com/input/?i=gradient+%28z^2-x^4-a^2%29%28y^2-x^4-a^2%2Bz^2%29

    and when I put (0,0,a) into the gradient I get (0,0,0).
    Are you sure you've copied out the Q correctly, because the modulus of a unit vector must be 1, and

    |(0,0,0)| \neq 1
 
 
 
Poll
Which web browser do you use?
Useful resources

Make your revision easier

Maths

Maths Forum posting guidelines

Not sure where to post? Read the updated guidelines here

Equations

How to use LaTex

Writing equations the easy way

Student revising

Study habits of A* students

Top tips from students who have already aced their exams

Study Planner

Create your own Study Planner

Never miss a deadline again

Polling station sign

Thinking about a maths degree?

Chat with other maths applicants

Can you help? Study help unanswered threads

Groups associated with this forum:

View associated groups

The Student Room, Get Revising and Marked by Teachers are trading names of The Student Room Group Ltd.

Register Number: 04666380 (England and Wales), VAT No. 806 8067 22 Registered Office: International House, Queens Road, Brighton, BN1 3XE

Quick reply
Reputation gems: You get these gems as you gain rep from other members for making good contributions and giving helpful advice.