Turn on thread page Beta
    • Thread Starter
    Offline

    4
    ReputationRep:
    Find and classify, the stationary points on the curves with parametric equations using first differential method. x=t^2 and y=t^3 -3t
    dy/dx= 3t^2-3/2t

    The stationary points are (1,2) when t =-1 and when t=1 the stationary point is (1,-2). The problem I'm having is when using first differential method I get that the points are inflection points, however this is wrong and they should be maximum and minimum points. Any help would be appreciated.
    Thanks
    Offline

    15
    ReputationRep:
    It may be useful to show your workings.
    Offline

    14
    ReputationRep:
    (Original post by gooner1010)
    Find and classify, the stationary points on the curves with parametric equations using first differential method. x=t^2 and y=t^3 -3t
    dy/dx= 3t^2-3/2t

    The stationary points are (1,2) when t =-1 and when t=1 the stationary point is (1,-2). The problem I'm having is when using first differential method I get that the points are inflection points, however this is wrong and they should be maximum and minimum points. Any help would be appreciated.
    Thanks
    Don't you mean second?
    Offline

    19
    ReputationRep:
    (Original post by gooner1010)
    Find and classify, the stationary points on the curves with parametric equations using first differential method. x=t^2 and y=t^3 -3t
    dy/dx= 3t^2-3/2t

    The stationary points are (1,2) when t =-1 and when t=1 the stationary point is (1,-2). The problem I'm having is when using first differential method I get that the points are inflection points, however this is wrong and they should be maximum and minimum points. Any help would be appreciated.
    Thanks
    How did you test your stationary points?
    • Thread Starter
    Offline

    4
    ReputationRep:
    (Original post by h3rmit)
    Don't you mean second?
    I tried second and I got the correct answer however the questions says use the first differential
    • Thread Starter
    Offline

    4
    ReputationRep:
    (Original post by gooner1010)
    I tried second and I got the correct answer however the questions says use the first differential
    Also for the spec im doing, they only expect you to know first differential
    Offline

    14
    ReputationRep:
    (Original post by gooner1010)
    I tried second and I got the correct answer however the questions says use the first differential
    That works too, with t=.9 and t=1.1, then the negatives
    • Thread Starter
    Offline

    4
    ReputationRep:
    (Original post by h3rmit)
    That works too, with t=.9 and t=1.1, then the negatives
    is there a specific range when using first differential method? I tried 0.5 and 1.5
    Offline

    14
    ReputationRep:
    (Original post by gooner1010)
    is there a specific range when using first differential method? I tried 0.5 and 1.5
    As close to the point you're using as possible is generally good idea, usually 0.1 or less away
    • Thread Starter
    Offline

    4
    ReputationRep:
    (Original post by h3rmit)
    That works too, with t=.9 and t=1.1, then the negatives
    When I put 0.9 I get a negative value and 1.1 get a positive value, wouldn't that be a point of inflection?
    Offline

    14
    ReputationRep:
    (Original post by gooner1010)
    When I put 0.9 I get a negative value and 1.1 get a positive value, wouldn't that be a point of inflection?
    No, positve on both sides or negative on both sides would be a point of inflection. Positive on one side and negative on the other means it's a turning point, like the hump of a cubic
    • Thread Starter
    Offline

    4
    ReputationRep:
    (Original post by h3rmit)
    No, positve on both sides or negative on both sides would be a point of inflection. Positive on one side and negative on the other means it's a turning point, like the hump of a cubic
    ahhh, I've got it now. Thankyou for the help
 
 
 
Reply
Submit reply
Turn on thread page Beta
Updated: February 4, 2017
Poll
Do you think parents should charge rent?
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

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