Hey there! Sign in to join this conversationNew here? Join for free
    • Thread Starter
    Offline

    0
    ReputationRep:
    Hey im struggling with this question on further rational functions and max and min points.

    Q: A curve has equation y = x^2-6 / x^2+4x+5

    a) prove that the curve only exists for -3< or equal to y< or equal to 2

    b) Hence determine the co-ordinates of stationary points of the curve.

    Ive tried a)

    I multiplied y by x^2+4x+5 which gives yx^2+4xy+5y - x^2+6 = 0

    then i tried to factor out the y's : (y-1)x^2 + y(4x+5) +6=0

    Then I would assume you would do b^2-4ac >(greather than or equal to) 0

    But by now I've made an error some where as that doesnt work (or maybe im doing it wrong lol).

    Please help.
    • Thread Starter
    Offline

    0
    ReputationRep:
    bump
    • Community Assistant
    Offline

    20
    ReputationRep:
    Community Assistant
    (Original post by marek35)
    bump
    You have the right idea but you lost the plot when forming your quadratic.

    You should have obtained:

    (y-1)x^2 + (4y)x + (5y+6) = 0
    • Thread Starter
    Offline

    0
    ReputationRep:
    (Original post by Mr M)
    You have the right idea but you lost the plot when forming your quadratic.

    You should have obtained:

    (y-1)x^2 + (4y)x + (5y+6) = 0
    lol Im guessing I messed up whereby a quadratic is in the form ax^2 +bx+c

    Makes sense.

    Cheers!

    EDIT: This is the problem ive been having all along.. getting them right now thanks Mr M!
    • Community Assistant
    Offline

    20
    ReputationRep:
    Community Assistant
    (Original post by marek35)
    lol Im guessing I messed up whereby a quadratic is in the form ax^2 +bx+c

    Makes sense.

    Cheers!

    EDIT: This is the problem ive been having all along.. getting them right now thanks Mr M!
    Good stuff.
 
 
 
Poll
Do you agree with the PM's proposal to cut tuition fees for some courses?
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.