Hey there! Sign in to join this conversationNew here? Join for free
    • Thread Starter
    Offline

    0
    ReputationRep:
    Using differentiation, find the turning points of the function y = x3 – 2x2 + 1 and sketch its curve.
    • Community Assistant
    • Welcome Squad
    Offline

    20
    ReputationRep:
    (Original post by Deannnn97)
    Using differentiation, find the turning points of the function y = x3 – 2x2 + 1 and sketch its curve.
    What about it? Will I get paid if I do your homework for you? Show some attempt!
    Offline

    21
    ReputationRep:
    (Original post by Deannnn97)
    Using differentiation, find the turning points of the function y = x3 – 2x2 + 1 and sketch its curve.
    dy/dx = 3x2 - 4x
    = x(3x - 4)
    Turning points are (0,0) (1.33,0)
    • Thread Starter
    Offline

    0
    ReputationRep:
    (Original post by Trapz99)
    dy/dx = 3x2 - 4x
    = x(3x - 4)
    Turning points are (0,0) (1.33,0)
    Thanks, so would this be a u shape or a n shape? I am not sure whether the shape comes from the +/-x or the +/- of the number?
    • Community Assistant
    Offline

    18
    ReputationRep:
    (Original post by Trapz99)
    dy/dx = 3x2 - 4x

    = x(3x - 4)
    Turning points are (0,0) (1.33,0)
    You missed a step, you need to sub the x values back into y to find the y coordinates at the stationary point.


    (Original post by Deannnn97)
    Thanks, so would this be a u shape or a n shape? I am not sure whether the shape comes from the +/-x or the +/- of the number?
    Neither, it's a cubic curve.
    Offline

    21
    ReputationRep:
    Sorry I misread the question.

    When you draw the graph for x3 - 2x2 + 1 that's a cubic curve and not u or n shaped
    • Community Assistant
    Offline

    18
    ReputationRep:
    (Original post by Trapz99)
    No I didn't miss anything.

    It's not a cubic curve. 3x2 - 4x doesn't have any cube
    That's \frac{dy}{dx}

    The curve is  y = x^3 - 2x^2 +1 written in the OP.
    Offline

    10
    ReputationRep:
    (Original post by Trapz99)
    Sorry I misread the question.

    When you draw the graph for x3 - 2x2 + 1 that's a cubic curve and not u or n shaped
    you need to sub your X values into the original equation for the stationary points, not the differential
    Offline

    21
    ReputationRep:
    The answer is:
    a) dy/dx = 3x2 - 4x
    0 = x (3x - 4)
    x = 1.33 x =0
    y = -5/27 y = 1
    So (1.33, -0.1852) and (0,1) are turning points
    Offline

    21
    ReputationRep:
    (Original post by Bananapeeler)
    you need to sub your X values into the original equation for the stationary points, not the differential
    Lol yeah I messed up
    Offline

    15
    ReputationRep:
    Do you understand why we have to use differentiation to be able to sketch the curve more accurately, or are you doing it for the sake of it?
    Offline

    16
    ReputationRep:
    (Original post by RDKGames)
    What about it? Will I get paid if I do your homework for you? Show some attempt!
    Homework at this time of year?
    • Community Assistant
    • Welcome Squad
    Offline

    20
    ReputationRep:
    (Original post by ODES_PDES)
    Homework at this time of year?
    Perhaps the summer schools are stepping it up a notch.
 
 
 
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • Poll
    Brussels sprouts
    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
  • See more of what you like on The Student Room

    You can personalise what you see on TSR. Tell us a little about yourself to get started.

  • 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.