Turn on thread page Beta
    • Thread Starter
    Offline

    12
    ReputationRep:
    i. Find the quotient and the remainder when 3x^3 -2x^2 + x +7 is divided by x^2-2x+5.
    = quotient =3x+4
    remainder = -6x - 13.
    ii. Hence, or otherwise, determine the values of the constants a and b such that, when 3x^3 -2x^2 +ax + b is divided by x^2 -2x+5, there is no remainder. ( 2 marks)

    The mark scheme states that a should be a =7 and b=20.

    I don't
    understand why 6 is added onto 1x instead of being taken away since it's -6x-13?
    • Community Assistant
    Offline

    20
    ReputationRep:
    Community Assistant
    (Original post by Chelsea12345)
    i. Find the quotient and the remainder when 3x^3 -2x^2 + x +7 is divided by x^2-2x+5.
    = quotient =3x+4
    remainder = -6x - 13.
    ii. Hence, or otherwise, determine the values of the constants a and b such that, when 3x^3 -2x^2 +ax + b is divided by x^2 -2x+5, there is no remainder. ( 2 marks)

    The mark scheme states that a should be a =7 and b=20.

    I don't
    understand why 6 is added onto 1x instead of being taken away since it's -6x-13?
    You ended up with:

    3x^3-2x^2+x+7 = (3x+4)(x^2-2x+5) + (-6x-13)

    We want the remainder to be 0, which means that if we add 6x+13 onto both sides we get 3x^3-2x^2+7x+20 = (3x+4)(x^2-2x+5). From here you can clearly read off the values of a,b by looking at the cubic on the left.
    • Thread Starter
    Offline

    12
    ReputationRep:
    i. Find the quotient and the remainder when 3x^3 -2x^2 + x +7 is divided by x^2-2x+5.
    = quotient =3x+4
    remainder = -6x - 13.
    ii. Hence, or otherwise, determine the values of the constants a and b such that, when 3x^3 -2x^2 +ax + b is divided by x^2 -2x+5, there is no remainder. ( 2 marks)

    The mark scheme states that a should be a =7 and b=20.

    I don't
    understand why 6 is added onto 1x instead of being taken away since it's -6x-13?
 
 
 
Reply
Submit reply
Turn on thread page Beta
Updated: March 5, 2018
Poll
Could you cope without Wifi?
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.