HELP Maths Question

Announcements Posted on
How helpful is our apprenticeship zone? Have your say with our short survey 02-12-2016
    • Thread Starter
    Offline

    1
    ReputationRep:
    The equation f(x) =0 has a repeated root, where f(x)=4x^2+px+q . When f (x) is divided by (x +1) the remainder is 1. Find the values of p and q.
    Offline

    3
    ReputationRep:
    (Original post by heatabi11)
    The equation f(x) =0 has a repeated root, where f(x)=4x^2+px+q . When f (x) is divided by (x +1) the remainder is 1. Find the values of p and q.
    If it has a repeated root then f(x) can be written in the form  (2x+a)^2 , and you know that  f(-1)=1 . Solve the simultaneous equations to find p and q.
    • Thread Starter
    Offline

    1
    ReputationRep:
    (Original post by Zacken)
    Blah blah, what's your attempt? What thoughts do you have? This isn't a do-my-homework-for-me site.
    my attempt got me to x=-1

    then substituting that in got 3+q=p

    was unsure how to go from there to get two sets of answers and add in the whole repeated root business
    Offline

    3
    ReputationRep:
    (Original post by heatabi11)
    my attempt got me to x=-1

    then substituting that in got 3+q=p

    was unsure how to go from there to get two sets of answers and add in the whole repeated root business
    Great progess! It'd have been so useful for you to have included that in the OP. Oh well, now you know for next time!

    You've got one equation in q and p, so you should be aiming to get another so you can solve simultaneously.

    What can you say about the discriminant of the quadratic if they have equal roots?
    Offline

    3
    ReputationRep:
    (Original post by Zacken)
    Blah blah, what's your attempt? What thoughts do you have? This isn't a do-my-homework-for-me site.
    Triggered. :awesome:
    • Thread Starter
    Offline

    1
    ReputationRep:
    (Original post by Zacken)
    Great progess! It'd have been so useful for you to have included that in the OP. Oh well, now you know for next time!

    You've got one equation in q and p, so you should be aiming to get another so you can solve simultaneously.

    What can you say about the discriminant of the quadratic if they have equal roots?
    woah didnt think of the discriminant what a spaz... the discriminant must be 0 yes?
    Offline

    3
    ReputationRep:
    (Original post by heatabi11)
    woah didnt think of the discriminant what a spaz... the discriminant must be 0 yes?
    Correct.

    so p-4q=0 ??
    Not so correct: discriminant is b^2 - 4ac = 0.
    • Thread Starter
    Offline

    1
    ReputationRep:
    (Original post by Zacken)
    Correct.



    Not so correct: discriminant is b^2 - 4ac = 0.
    ya i deleted that so p^2-16q=0
    Offline

    3
    ReputationRep:
    (Original post by heatabi11)
    ya i deleted that so p^2-16q=0
    Yes. Now sub in p = 3+q and solve.
    • Thread Starter
    Offline

    1
    ReputationRep:
    (Original post by Zacken)
    Yes. Now sub in p = 3+q and solve.
    woah thanks man you literally saved me
    Offline

    3
    ReputationRep:
    (Original post by heatabi11)
    woah thanks man you literally saved me
    You're welcome, just make sure to provide your own thoughts/attempts in the OP in the future, thanks.
 
 
 
Write a reply… Reply
Submit reply

Register

Thanks for posting! You just need to create an account in order to submit the post
  1. this can't be left blank
    that username has been taken, please choose another Forgotten your password?
  2. this can't be left blank
    this email is already registered. Forgotten your password?
  3. this can't be left blank

    6 characters or longer with both numbers and letters is safer

  4. this can't be left empty
    your full birthday is required
  1. Oops, you need to agree to our Ts&Cs to register
  2. Slide to join now Processing…

Updated: September 18, 2016
TSR Support Team

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

Today on TSR
Poll
Would you rather have...?
Useful resources

Make your revision easier

Maths

Maths Forum posting guidelines

Not sure where to post? Read here first

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
Study resources

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.