Hey there! Sign in to join this conversationNew here? Join for free

Polynomials Watch

Announcements
    • Thread Starter
    Offline

    0
    ReputationRep:
    the cubic polynomial 2x^3-5x^2+ax+b is denoted by f(x). It is given that (x-2) is a factor of f(x),and that when f(x) is divided by (x-1) the remainder is -6. find the values of a and b.
    • TSR Support Team
    • Study Helper
    Offline

    20
    ReputationRep:
    (Original post by TumiZN)
    the cubic polynomial 2x^3-5x^2+ax+b is denoted by f(x). It is given that (x-2) is a factor of f(x),and that when f(x) is divided by (x-1) the remainder is -6. find the values of a and b.
    Any ideas? Do you know the factor theorem?
    Offline

    15
    ReputationRep:
    (Original post by TumiZN)
    the cubic polynomial 2x^3-5x^2+ax+b is denoted by f(x). It is given that (x-2) is a factor of f(x),and that when f(x) is divided by (x-1) the remainder is -6. find the values of a and b.
    use the factor/remainder theorem and set 2 simultaneous equations
    • Thread Starter
    Offline

    0
    ReputationRep:
    (Original post by notnek)
    Any ideas? Do you know the factor theorem?
    In class doing the question is easy but once at home it is as though a part of my brain shuts off
    • TSR Support Team
    • Study Helper
    Offline

    20
    ReputationRep:
    (Original post by TumiZN)
    In class doing the question is easy but once at home it is as though a part of my brain shuts off
    Ok I'll start you off:

    If (x-2) is a factor of f(x) then this means that f(2) must be equal to 0.

    To find f(2), you need to substitute 2 into 2x^3-5x^2+ax+b. Then set this to 0.


    If (x-1) divided gives a remainder of -6 it means that f(1) = -6.


    Have a go at this now and post all your working if you get stuck - it doesn't matter if your working is wrong.
    • Thread Starter
    Offline

    0
    ReputationRep:
    (Original post by notnek)
    Ok I'll start you off:

    If (x-2) is a factor of f(x) then this means that f(2) must be equal to 0.

    To find f(2), you need to substitute 2 into 2x^3-5x^2+ax+b. Then set this to 0.


    If (x-1) divided gives a remainder of -6 it means that f(1) = -6.


    Have a go at this now and post all your working if you get stuck - it doesn't matter if your working is wrong.
    Thank you , you made it easier to understand
 
 
 
  • 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.

  • Break up or unrequited love?
    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.