Basic c2 graphs question

Maths and statistics discussion, revision, exam and homework help.

Announcements Posted on
TSR launches Learn Together! - Our new subscription to help improve your learning 16-05-2013
IMPORTANT: You must wait until midnight (morning exams)/4.30AM (afternoon exams) to discuss Edexcel exams and until 1pm/6pm the following day for STEP and IB exams. Please read before posting, including for rules for practical and oral exams. 28-04-2013
Sign in to Reply
  1. IShouldBeRevising_'s Avatar
    • Benevolent Member
    • Location: In a house
    • Posts: 815
    Basic c2 graphs question
    Say you are given the equation y = x(x^2-1) to sketch the roots are (-1,0) (0,0) (1,0)

    How would you sketch it I mean in terms of which side would you start of with how do you know where the max min points are.

    Also does anybody know what the graph of y=-srt of x look like?
  2. raheem94's Avatar
    • TSR Demigod
    • Posts: 5,512
    Re: Basic c2 graphs question
    (Original post by IShouldBeRevising_)
    Say you are given the equation y = x(x^2-1) to sketch the roots are (-1,0) (0,0) (1,0)

    How would you sketch it I mean in terms of which side would you start of with how do you know where the max min points are.

    Also does anybody know what the graph of y=-srt of x look like?
    The graph of  y= - \sqrt{x} looks like this:



    For the graph of,  y=x(x^2-1)

    You know the values where it crosses the x-axis, just consider all the regions, by subbing in some values to deduce the shape of the graph.

    e.g. It crosses at (1,0), see what is the value of y when x=2, if it is positive then the graph will move upward and if it is negative, then the graph will move downwards.
  3. raheem94's Avatar
    • TSR Demigod
    • Posts: 5,512
    Re: Basic c2 graphs question
    (Original post by IShouldBeRevising_)
    Say you are given the equation y = x(x^2-1) to sketch the roots are (-1,0) (0,0) (1,0)

    How would you sketch it I mean in terms of which side would you start of with how do you know where the max min points are.

    Also does anybody know what the graph of y=-srt of x look like?
    I forgot to answer your other question about max/min points.

    Max/min occurs at stationary points where the gradient is equal to zero.

     y=x(x^2-1) = x^3-x

    Differentiate the above expression, and set dy/dx=0 to find the stationary points. Find the 2nd derivative to check whether the points are max or min.
  4. IShouldBeRevising_'s Avatar
    • Benevolent Member
    • Location: In a house
    • Posts: 815
    Re: Basic c2 graphs question
    (Original post by raheem94)
    I forgot to answer your other question about max/min points.

    Max/min occurs at stationary points where the gradient is equal to zero.

     y=x(x^2-1) = x^3-x

    Differentiate the above expression, and set dy/dx=0 to find the stationary points. Find the 2nd derivative to check whether the points are max or min.

    (Original post by raheem94)
    The graph of  y= - \sqrt{x} looks like this:



    For the graph of,  y=x(x^2-1)

    You know the values where it crosses the x-axis, just consider all the regions, by subbing in some values to deduce the shape of the graph.

    e.g. It crosses at (1,0), see what is the value of y when x=2, if it is positive then the graph will move upward and if it is negative, then the graph will move downwards.
    Thanks well explained... I get it now
Sign in to Reply
Share this discussion:  
Article updates
Moderators

We have a brilliant team of more than 60 volunteers looking after discussions on The Student Room, helping to make it a fun, safe and useful place to hang out.

Reputation gems:
The Reputation gems seen here indicate how well reputed the user is, red gem indicate negative reputation and green indicates a good rep.
Post rating score:
These scores show if a post has been positively or negatively rated by our members.