Turn on thread page Beta
    • Thread Starter
    Offline

    12
    ReputationRep:
    The cubic polynomial f(x) is defined by f(x) = x^3 + ax^2 – ax – 14, where a is a constant. (i) Given that (x – 2) is a factor of f(x), find the value of a.
    • Community Assistant
    Offline

    20
    ReputationRep:
    Community Assistant
    (Original post by Chelsea12345)
    The cubic polynomial f(x) is defined by f(x) = x^3 + ax^2 – ax – 14, where a is a constant. (i) Given that (x – 2) is a factor of f(x), find the value of a.
    Can you show your working? You should be making use of your knowledge of the factor theorem if you don't know where to start.
    Offline

    11
    ReputationRep:
    (Original post by Chelsea12345)
    The cubic polynomial f(x) is defined by f(x) = x^3 + ax^2 – ax – 14, where a is a constant. (i) Given that (x – 2) is a factor of f(x), find the value of a.
    The factor theorem states, if  x-b is a factor of  f(x) , this implies  f(b) = 0
    Offline

    3
    ReputationRep:
    A factor means y is zero when x is a
    • Thread Starter
    Offline

    12
    ReputationRep:
    (Original post by Naruke)
    The factor theorem states, if  x-a is a factor of  f(x) , this implies  f(a) = 0
    so should i try random number in place of x like 1,3?
    Offline

    11
    ReputationRep:
    (Original post by Chelsea12345)
    so should i try random number in place of x like 1,3?
    Read my above post again, I had to edit it.

    I didn't notice that the letter 'a' was also used in your question.
    • Community Assistant
    Offline

    20
    ReputationRep:
    Community Assistant
    (Original post by Chelsea12345)
    so should i try random number in place of x like 1,3?
    No. f(2)=0 because (x-2) is a factor.
    • Thread Starter
    Offline

    12
    ReputationRep:
    i got a=3 . is that right?
    • Community Assistant
    Offline

    20
    ReputationRep:
    Community Assistant
    (Original post by Chelsea12345)
    i got a=3 . is that right?
    Yes.
 
 
 
Reply
Submit reply
Turn on thread page Beta
Updated: January 12, 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.